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SUGGESTIONS  TO  TEACHERS 


DESIGNED   TO    ACCOMPANY 


THE   ELEMENTARY   PRINCIPLES 
OF  CHEMISTRY 


BY 

A.  V.   E.  YOUNG 

PROFESSOR   OF   CHEMISTRY    IN    NORTHWESTERN    UNIVERSITY 


NEW    YORK 

D.    APPLETON    AND   COMPANY 
1901 


TWENTIETH   CENTURY   TEXT-BOOKS 


SUGGESTIONS  TO  TEACHERS 

DESIGNED   TO    ACCOMPANY 

THE   ELEMENTARY  PRINCIPLES 
OF  CHEMISTRY 


BY 

A.  V.   E.  YOUNG 

PROFESSOR   OF   CHEMISTRY    IN    NORTHWESTERN    UNIVERSITY 


NEW    YORK 

D.    APPLETON   AND   COMPANY 
1901 


COPYRIGHT,  1901 
BY   D.   APPLETON   AND    COMPANY 


TO  THE  TEACHER  OF  CHEMISTRY 

THE  following  suggestions  are  designed  to  accompany 
the  text-book  of  the  writer.  His  desire  is  to  assist  the 
teacher  of  a  subject  that  draws  heavily  on  time  and 
strength,  not  only  for  the  work  of  instruction,  but  for 
the  preparation  and  care  of  material  and  for  the  man- 
agement of  the  laboratory.  As  the  intention,  frankly 
avowed,  is  to  describe  very  informally  my  own  methods, 
I  judge  that  I  may  be  pardoned  the  use  of  the  first 
person  singular. 


184368 


A.  V.  E.  Y. 

iii 


\ 

Of  THE 

UNIVERSITY 


THE   ELEMENTARY  PRINCIPLES   OP 
CHEMISTRY 


SUGGESTIONS  TO   TEACHEES 

i 
INTRODUCTION 

THE  place  of  chemistry  in  education  as  a  branch  of 
natural  science  is  fairly  well  recognized.  The  value  of  its 
training  for  close  observation,  clear  thinking,  and  precise 
expression  is  widely  admitted,  as  is  also  the  applicability 
of  much  of  its  subject-matter  to  practical  affairs.  But  I 
sometimes  think  that  those  who  stand  as  its  advocates,  and 
perhaps  its  teachers  also,  do  not  sufficiently  emphasize  the 
dignity  and  worth  which  pertain  to  it  as  a  serious  study  of 
nature,  of  nature  in  the  broadest  significance  of  the  term ; 
for  surely  that  which  elevates  and  ennobles  should  be 
found,  if  it  be  sought,  in  the  wonders  of  material  creation, 
the  handiwork  of  infinite  intelligence,  as  truly  as  in  the 
history  of  men's  achievements  in  material  things. 

I  am  not  so  sure  that  the  laboratory  method  for  chem- 
istry has  received  as  general  assent  as  has  the  claim  in 
behalf  of  the  science  for  a  place  in  the  curriculum.  For 
my  part,  I  almost  think  that  in  the  interest  of  the  pupils 
their  time  may  better  be  given  to  some  other  subject,  unless 
suitable  laboratory  study  can  be  provided.  I  shall  assume, 
therefore,  that  the  laboratory  method  is  adopted.  The 
quantitative  method  in  the  laboratory  is  still  further  from 
receiving  universal  approval,  and  to  this,  attention  is  here 

84368 


2      THE  ELEMENTARY  PRINCIPLES  OF  CHEMISTRY 

invited  since  the  course  herewith  offered  is  based  upon  it. 
The  quantitative  method  aims  to  bring  the  student  into 
direct  contact,  so  to  speak,  with  the  relations  of  quantity  as 
well  as  with  those  of  quality.  It  most  distinctly  does  not 
aim  to  present  the  systematic  methods  of  quantitative  analy- 
sis. No  more  does  it  propose  that  the  pupil  shall  prove  to 
his  own  mind  the  laws  of  quantity.  Such  laws  are  induc- 
tions from  a  great  many  observations,  arid  the  student 
should  be  carefully  guarded  against  the  idea  that  his  ex- 
periments are  to  prove  them,  even  to  his  own  conviction. 
His  experimentation  is  simply  to  aid  him  by  direct  observa- 
tion and  by  guided  thought  to  get  a  clear  notion  of  the 
content  and  meaning  of  the  laws.  The  relations  of  quan- 
tity are  absolutely  fundamental  to  the  science.  No  branch 
of  physical  science  has  made  any  considerable  progress 
until  it  has  been  placed  on  a  quantitative  basis.  There- 
fore there  is  the  same  desirability  to  illustrate  for  the 
student  the  quantitative  aspect  of  things  as  there  is  to 
illustrate  their  properties  in  descriptive  experiments. 
Moreover,  it  is  desirable  that  quantity  shall  receive  due 
consideration  and  illustration  at  the  moment  when  the  logic 
of  the  subject  calls  for  the  same,  and  that  is  early  in  the 
course.  I  believe  it  also  a  positive  advantage  that  the 
careful  manipulation  which  is  necessary  when  attention  is 
given  to  quantity  should  come  at  the  outset  of  the  stu- 
dent's experience  rather  than  after  he  has  formed  the 
habit  of  disregarding  quantity.  In  addition,  it  may  be 
claimed  that  the  quantitative  method,  speaking  broadly, 
contributes  very  considerably  to  the  disciplinary  value  of 
any  branch  of  natural  science.  It  is  this  which  gives  to 
the  subject  of  Physics  its  advantage  over  other  branches. 

But  whatever  may  be  said  as  to  the  desirability  of  these 
things,  the  use  of  the  method  must  be  limited  by  its  prac- 
ticability. Probably  the  first  objection  to  be  urged  is  the 
impracticability  of  providing  the  necessary  equipment.  Of 
this  the  balance  is  the  essential  feature.  If  it  were  de- 


SUGGESTIONS  TO   TEACHERS  3 

manded  that  this  should  be  a  balance  capable  of  weighing 
to  one  ten-thousandth  of  a  gram,  the  impracticability  of  the 
thing  would  be  manifest.  Not  only  this,  but  it  would  be 
folly  to  try  to  use  such  a  balance  if  it  were  provided.  One 
which  weighs  to  the  hundredth  of  a  gram  is  all  that  is 
called  for,  and  this  is  surely  within  the  range  of  the  prac- 
ticable. The  rest  of  the  equipment  is  hardly  more  than  is 
provided  for  the  usual  courses. 

The  next  objection  to  be  expected  is  that  the  beginning 
pupil  has  not  sufficient  skill  in  manipulation  to  do  the 
work.  This  may  be  true,  but  it  is  equally  true  that  he  can 
very  quickly  acquire  that  skill.  No  one,  not  even  the  most 
advanced  worker,  has  skill  until  he  acquires  it.  And  the 
only  way  to  get  skill  is  to  do,  and  of  all  doing  there  must 
be  a  beginning.  The  pupil  may  just  as  well  learn  to  use 
the  balance  by  using  it  the  first  day  in  the  laboratory,  as 
by  deferring  its  use  until  he  has  worked  a  year,  if  in  the 
meantime  he  never  touches  it.  I  have  in  mind,  of  course, 
a  balance  like  the  one  just  specified,  nothing  finer. 

Another  objection  is  that  quantitative  experiments  take 
more  time  than  do  descriptive  experiments.  This  is  true, 
but  before  the  former  are  condemned  for  this  reason,  it 
should  be  duly  considered  that  they  are  used  to  lead  the 
student  to  a  clear  notion  of  fundamental  laws  which  are 
based  on  broad  generalizations,  and,  if  this  is  gained,  it  is 
worth  the  greater  expenditure  of  time.  Suppose  the  pupil 
could  make  a  dozen  experiments  descriptive  of  some  sub- 
stance or  substances  in  the  time  needed  for  the  quanti- 
tative experiment  illustrating  multiple  proportions,  does' it 
follow  that  the  time  is  spent  to  better  advantage  in  the 
former  ?  Indeed,  there  may  be  positive  gain  in  the  fact 
that  the  student  must  work  slowly  and  deliberately  at  the 
outset,  when  he  is  getting  the  fundamental  notions  of  the 
subject.  This,  if  not  carried  to  excess,  may  help  to  make 
the  laboratory  what  it  should  be — a  place  for  thinking  as 
well  as  for  seeing.  Nor  should  it  be  overlooked  that  items 


4      THE  ELEMENTARY  PRINCIPLES  OF  CHEMISTRY 

of  description  also  occur  in  the  quantitative  experiments, 
although  description  is  subordinate  to  the  main  idea. 

Finally,  it  may  be  objected  that  with  the  limitations  of 
equipment  and  of  manipulative  skill  already  suggested,  the 
quantitative  results  obtainable  are  worthless.  The  truth 
of  this  depends  on  how  the  results  are  used.  If  they  are 
used  with  any  pretense  to  prove  laws,  they  are  worthless 
for  the  purpose  ;  but  if  they  suffice  to  bring  to  the  stu- 
dent's mind  the  relation  of  quantities  within  the  limits  of 
his  observational  accuracy,  the  point  is  made.  Therefore 
it  is  reckoned  essential  to  the  satisfactory  use  of  the  quan- 
titative method  that  the  limits  of  accuracy  be  carefully 
estimated  for  each  experiment.  The  teacher  is  urged  to 
keep  this  constantly  before  his  pupils.  For  a  concrete  ex- 
ample, take  the  experiments  Nos.  41/3  and  41/4  in  which 
the  student  determines  the  volume  and  mass  of  hydrogen 
liberated  by  2.4  grams  of  magnesium  and  6.5  grams  of  zinc, 
as  illustration  of  equivalent  proportions.  If  he  makes  two 
determinations  of  the  value  for  each  metal,  and  finds  that 
the  value  for  zinc  does  not  differ  from  that  for  magnesium 
more  than  one  value  for  magnesium  differs  from  the  other 
for  the  same,  or  one  zinc  from  the  other  zinc,  then  the 
experiment  has  served  its  purpose  to  bring  to  his  observa- 
tion and  to  impress  upon  his  mind  the  relation  of  equiva- 
lency within  the  limits  of  his  observational  accuracy.  It 
should  not  be  forgotten  that  this  careful  consideration  of 
the  limitations  to  accuracy  is  necessary  in  all  experimental 
results,  even  in  those  obtained  by  the  most  skillful  experi- 
menters and  with  the  most  refined  apparatus. 

TIME  AND  TOPICS 

One  of  the  first  things  to  which  a  teacher  must  recon- 
cile himself  is  the  fact  that  he  can  not  teach  to  beginners 
in  a  course  of  one  year  the  whole  of  the  science.  Even 
if  he  were  willing  to  make  information  the  sole  end  of  his 
teaching,  he  could  not  present  all  the  so-called  useful  in- 


SUGGESTIONS  TO  TEACHERS  5 

formation  of  the  subject  of  chemistry.  But  training  is, 
after  all,  a  fundamental  purpose  of  education,  and  it  may 
be  reckoned  as  one  of  the  peculiar  advantages  of  our  sub- 
ject that  training  and  useful  information  are  so  effectively 
combined.  In  choosing  topics,  therefore,  both  these  fea- 
tures must  be  carefully  considered  as  well  as  the  limita- 
tions of  time. 

I  assume  an  aggregate  time  not  less  than  four  periods 
a  week  through  the  academic  year  of  thirty-eight  or 
forty  weeks ;  also  that  the  quantitative  method  in  the 
laboratory  is  accepted.  I  also  assume  a  maturity  (with  no 
previous  chemical  instruction,  however)  on  the  part  of  the 
student,  which  I  estimate  is  attained  by  the  average  pupil 
in  the  last  year  of  his  high  school  experience  or  the  first 
year  of  college  ;  and  I  must  be  permitted  to  decline  sponsor- 
ship for  the  course  outside  of  these  conditions.  But  four 
periods  a  week  may  not  always  mean  the  same  amount  of 
available  time.  Sessions  limited  to  one  hour  or  less  are 
very  uneconomical  of  time  for  laboratory  study,  and  make 
it  almost  impracticable.  Two,  or  at  least  one  and  a  half, 
hours  of  uninterrupted  time  should  be  provided,  and  two 
hours  of  laboratory  time  should  be  reckoned  as  one  of  pre- 
pared recitation. 

In  my  own  classes  the  time  assignment  is  four  hours 
a  week,  but  this  is  interpreted  as  allowing  eight  hours  of 
aggregate  time  to  the  subject,  either  in  the  class  room  or 
in  the  laboratory.  It  is  an  advantage  to  have  the  time 
assigned  for  class  room  work  continuous  with  that  for  the 
laboratory.  This  permits  of  adjustment  according  to  the 
demands  of  a  particular  topic.  I  therefore  have  three  ses- 
sions a  week  of  two  and  a  third  hours  each,  thus  taking 
seven  hours  and  allowing  a  margin  of  one  hour  for  work 
outside  of  the  laboratory  and  of  the  class  room. 

If  it  is  necessary  to  divide  a  class  into  sections  for  lab- 
oratory work,  there  is  advantage  in  having  successive  days 
for  each  section — e.  g.,  Monday  and  Friday  for  one,  and 


6       THE  ELEMENTARY  PRINCIPLES  OF  CHEMISTRY 

Tuesday,  Wednesday,  and  Thursday  for  another — as  pupils 
can  thus  suspend  work  on  an  unfinished  experiment  with 
less  inconvenience.  However,  this  advantage  may  be  over- 
balanced by  the  difficulty  of  securing  such  allotment  of 
time.  With  the  arrangement  that  has  been  indicated,  I 
allow  thirty-five  weeks,  vacations  not  included,  for  complet- 
ing the  course  offered  in  the  text.  But  inasmuch  as  the 
amount  of  work  accomplished  is  likely  to  vary  considerably, 
even  with  the  same  time  assignment,  it  may  be  helpful  if  I 
give  more  in  detail  an  estimate  of  the  time  needed  for  the 
several  portions  of  the  course  : 

Chapter  I,  6  weeks. 

Chapter  II,  6  weeks. 

Chapters  III  and  IV,  2  'weeks. 

Chapter  V,  Law  1,  3  weeks  ;  Laws  2  and  3, 1  week  ;  Laws 
4  and  5,  2  weeks. 

Chapter  VI  and  VII,  3  weeks. 

Chapter  VIII,  12  weeks. 

If  circumstances  make  it  necessary  to  curtail  the  course, 
the  following  expedients  are  suggested  : 

1.  To  waive  the  requirement  of  two  good  quantitative 
results  from  each  student.     If  this  is  done,  care  should  be 
taken  to  bring  before  the  whole  class  a  sufficient  number 
of  the  individual  results  to  show  the  range  of  variation. 

2.  Under  the  law  of  equivalent  proportions,  Chapter  II, 
the  four  parts  of  the  experiment  might  be  assigned  to  dif- 
ferent members  of  the  class.     Some  could  be  asked  to  de- 
termine the  hydrogen   with  magnesium  and  the   oxygen 
with  zinc  ;  others  to  determine  the  hydrogen  with  zinc  and 
the  oxygen  with  magnesium — some  by  the  first  method  and 
some  by  the  second.     In  a  similar  manner  the  problem  of 
determining  the  vapor-density  of  carbon  dioxide,  Chapter 
V,  Law  1,  might  be  divided,  the  determination  of  weight 
being  assigned  to  a  part  of  the  class  and  that  of  volume  to 
another  part.     An  expedient  of  this  kind  is  a  sacrifice,  for 
it  is  very  desirable  that  the  student's  work  should  be  thor- 


SUGGESTIONS  TO  TEACHERS  f 

oughly  individual.  If  it  is  used  the  teacher  needs  to  see 
that  the  class  room  discussion  makes  clear  to  each  one  how 
his  neighbor's  observation  supplements  his  own. 

3.  If  curtailment  of  topics  is  necessary,  it  is  suggested 
that  Chapter  IV  may  be  unnecessary  in  case  the  class  has 
previously  studied  these  topics  in  physics.     The  same  may 
be  said  as  to  the  experiments  in  specific  heat  (Chapter  V, 
Law  2),  which,  like  the  preceding,  involve  no  chemical  re- 
actions.    These  experiments  and  the  accompanying  calcu- 
lations are  very  helpful  in  clarifying  the  student's  ideas. 
Especially  is  this  true  as  to  the  laws  of  Raoult  (4  and  5, 
Chapter  Y),  and  it  justifies  the  use  of  the  latter  experi- 
ments, notwithstanding  the  crudeness  of  the  quantitative 
results  which  are  attainable. 

Chapter  VI  reinforces  what  has  already  been  defined 
and  repeatedly  discussed,  and  I  judge  the  experiments  are 
worth  the  time  given  to  them  for  this  purpose,  but  they 
might  be  omitted  rather  than  sacrifice  altogether  some 
other  topic. 

As  to  the  last  part  of  Chapter  VII,  beginning  with 
"  Evidence  as  to  structure,"  Xo.  181,  its  utility  may  be 
doubted.  I  am  in  the  habit  of  giving  it  to  my  classes  with 
the  idea  that  they  may  get  some  impression  from  it.  Many 
probably  would  prefer  to  omit  it  altogether.  For  my  part, 
I  would  readily  assent  to  having  the  whole  of  Chapter  VII 
dropped,  although  this  would  generally  be  regarded  as  too 
radical  a  step.  I  believe  that  first-year  courses  of  chem- 
istry would  be  bettered  if  the  conception  of  atoms  and 
molecules  were  not  introduced  at  all,  and  that  if  teachers 
would  make  their  presentation  of  the  science  independent 
of  the  atomic  hypothesis  as  a  basis  they  would  come  to 
regard  it  as  a  genuine  emancipation. 

4.  Finally,  it  is  suggested  that  when  the  class  reaches 
Chapter  V  the  teacher  follow  this  plan  if  he  is  in  doubt 
about  completing  the  course  without  curtailment,  viz.  :  To 
take  up  Chapter  VIII  either  before  entering  on  Chapter  V 


8      THE  ELEMENTARY  PRINCIPLES  OF   CHEMISTRY 

or  after  completing  Gay-Lussac's  Law  ;  then  after  Chapter 
VIII  to  No.  642  is  finished,  to  turn  back  fco  Chapter  V  and 
present  the  remaining  text  with  such  curtailment  as  limit 
of  time  may  necessitate.  It  is  difficult  for  a  teacher  to 
foresee  without  actual  trial  how  a  text  will  adapt  itself 
to  time.  Some  may  prefer,  aside  from  the  question  of 
time  limit,  to  introduce  the  descriptive  matter  before  the 
topics  of  Chapters  V,  VI,  and  VII ;  and  I  see  no  serious 
objection  nor  difficulty  in  so  doing,  although  in  my  own 
practice  I  prefer  to  follow  the  order  of  the  text.  There  are 
a  few  references  in  Chapter  VIII  to  the  matter  of  Chap- 
ters V,  VI,  and  VII,  especially  as  to  vapor-density,  and  over 
these  points  the  teacher  might  need  to  help  the  student 
temporarily.  Such  references  occur  in  Nos.  208/2,  314,  323, 
331,  434,  436,  461,  493,  494,  and  640.  I  cite  these  so  that 
the  teacher  may  judge  for  himself  as  to  the  practicability 
of  departing  from  the  order  of  the  text  in  the  manner  sug- 
gested. In  Chapter  VIII  the  matter  pertaining  to  indus- 
trial applications  and  to  other  items  not  essential  to  the 
unity  of  the  course  is  set  apart  so  that  the  teacher  may 
use  it  or  not,  at  his  discretion.  Pupils  are  likely  to  read 
such  matter  from  general  interest,  and  it  does  not  call  for 
the  time  and  effort  of  deliberate  study. 

Criticism  is  anticipated  upon  the  fullness  of  treatment 
in  Chapter  V,  especially  as  to  use  of  the  tabulated  data. 
There  is  a  distinct  motive  for  this.  Few,  I  judge,  would 
favor  the  omission  of  these  topics ;  and  it  is  of  prime  impor- 
tance that  the  student  should  realize  that  these  laws  are 
inductions  from  observed  data,  and  furthermore  that  they 
are  approximations  of  a  very  different  order  of  exactness  as 
compared  with  that  of  the  laws  of  proportion  in  Chapter 
II.  To  present  them  as  laws  without  this  qualification  is 
to  be  false  to  fact,  and  leads  the  student  naturally  to  infer 
that  which  is  not  true.  To  avoid  this  error,  therefore,  the 
data  are  presented,  and  not  at  all  with  the  intention  that 
the  student  shall  commit  them  to  memory.  Some,  per- 


SUGGESTIONS  TO  TEACHERS  9 

haps,  would  wish  to  include  additional  topics  of  similar 
import,  such  as  osmotic  pressure  and  the  electrical  phe- 
nomena of  conductivity,  etc.,  together  with  the  theory  of 
ionization ;  but  I  have  judged  it  impracticable  to  illustrate 
these  phenomena  experimentally  without  displacing  other 
matter  or  going  beyond  the  reasonable  scope  of  one  year's 
work ;  and  therefore  I  have  deemed  it  best  not  to  include 
either  them  or  the  theory. 

As  TO  TOPICS  AND  EXPERIMENTS  IN  DETAIL 

References  are  to  marginal  numbers  in  Parts  I  and  II  of  the  text. 

It  is  suggested  that  the  teacher  at  the  outset  either 
have  the  pupils  read  Numbers  1  to  6,  Part  I,  or  that  he 
give  the  class  the  substance  of  these  paragraphs  in  an  in- 
formal talk  immediately  before  they  pass  into  the  labora- 
tory to  begin  work.  In  the  laboratory  it  is  well  to  begin 
by  naming  over  the  articles  of  apparatus  in  the  individual 
equipment,  letting  the  class  identify  each  by  the  sample 
shown  from  the  instructor's  table,  then  to  direct  attention 
to  the  Recommendation  as  to  Notes.  I  also  emphasize  in 
this  preliminary  talk  that  the  laboratory  is  a  place  for  seri- 
ous study  and  work  and  not  for  amusement.  Then  each 
pupil  being  at  his  place  with  a  sample  of  roll  sulphur  and 
his  directions  before  him,  I  call  attention  to  each  item 
(Numbers  1  to  6),  explaining  that  crystalline  form  is  dif- 
ferent from  the  chance  shape  of  each  fragment  or  the 
form  given  by  the  mold.  The  commercial  samples  of  roll 
sulphur  or  brimstone  do  not  often  show  crystalline  forms 
large  enough  to  be  apparent.  The  larger  crystals  are  seen 
in  Number  12/j. 

Number  7. — This  involves  the  first  weighing,  and  atten- 
tion is  directed  to  the  Appendix,  1.  It  is  well  for  the 
instructor  to  show  from  the  demonstration  table  the  ma- 
nipulation of  sorting  the  lumps,  corking  the  test-tube 
while  holding  it  in  the  full  palm  to  avoid  the  danger  of 
crushing,  then  of  wiping  and  of  weighing. 


10    THE  ELEMENTARY  PRINCIPLES  OF  CHEMISTRY 

It  is  recommended  that  pupils  be  called  on  in  the  class 
room  to  read  their  experimental  notes ;  then  that  correc- 
tions and  additions  be  called  for  from  the  class ;  and  finally 
that  the  instructor  by  questions,  and  perhaps  added  state- 
ments, complete  the  discussion  of  the  topic.  My  plan  is 
to  have  the  pupils  enter  on  the  left-hand  page  such  correc- 
tions and  additions  as  are  brought  out  in  this  discussion. 
After  this  reading  and  discussion  of  the  observations  fol- 
lows the  fuller  presentation  of  Part  I. 

In  calculating  the  specific  gravity  of  sulphur,  the  error 
is  very  commonly  made  of  subtracting  the  weight  of  the 
tube  filled  with  water  from  the  weight  of  the  tube  contain- 
ing water  and  sulphur  and  calling  the  difference  the  weight 
of  the  water  displaced.  Since  the  specific  gravity  of  sul- 
phur is  2,  this  error  still  gives  a  good  numerical  result,  and 
the,  incident  affords  the  opportunity  to  show  the  need,  not 
alone  of  a  correct  final  result,  but  of  correct  reasoning  and 
method.  Since  this  experiment  involves  quantitative  meas- 
urement, it  is  well  to  bring  out  an  important  matter,  after 
a  record  has  been  read,  by  questions  somewhat  like  these  : 
You  say  your  sulphur  weighed  10  grams ;  how  do  you  know 
that  ?  How  do  you  know  that  the  weight  was  not  10.001 
grams?  Do  you  know  that  it  was  not  10.01  ?  How  closely 
did  you  measure  the  quantity  you  have  called  10  grams  ? 
I  do  not  generally  give  out  the  hundredth-gram  weights 
until  later  in  the  course,  when  they  are  specifically  called 
for  in  the  directions,  so  only  tenths  are  used  here.  With 
these  and  the  balance  which  is  capable  of  indicating 
hundredths,  they  estimate  to  .05  of  a  gram  with  an 
uncertainty  of  0.02  or  0.03.  Well,  then,  I  ask,  if  there 
is  an  uncertainty  of  0.02  in  each  weighing,  how  much 
uncertainty  attaches  to  the  final  result?  (About  0.02 
or  0.03.)  This  I  let  them  figure  out.  I  then  explain  that 
similar  estimates  of  uncertainty  are  involved  in  all  obser- 
vations of  quantity,  no  matter  how  refined  the  methods. 
Then  I  usually  put  the  questions  suggested  in  Num- 


SUGGESTIONS  TO  TEA 


ber  8,  and  thus  lead  the  way  to  the  fuller  statements  of 
Part  I. 

Numbers  10,  11,  12.— The  teacher  should  manipulate 
this  experiment  before  the  class,  by  way  of  instruction. 
Students  will  sometimes  fail  to  get  a  good  sample  of  the 
plastic  form,  because  they  do  not  heat  sufficiently  before 
pouring  into  water ;  if  so,  I  have  them  try  again.  As  there 
is  no  change  in  weight  in  passing  from  the  plastic  to  the 
brittle  condition,  it  is,  of  course,  important  that  the  sam- 
ple shall  be  well  dried  before  it  is  weighed,  hence  the  direc- 
tion to  string  it  out ;  otherwise  the  drying  is  difficult. 

Numbers  12/i  and  12/2,  I  do  not  allow  the  class  to  per- 
form, but  myself  prepare  the  crystals  from  fusion  shortly 
before  they  are  to  be  exhibited.  For  this  purpose  a  Hessian 
crucible  is  used.  I  prepare  the  solution  in  carbon  disul- 
phide  at  the  lecture  table  and  set  it  aside  for  crystalliza- 
tion and  later  examination. 

Number  13/1( — The  zinc  must  be  the  very  fine  powder 
commercially  called  zinc  dust,  but  this  even  does  not  always 
react  with  equal  readiness,  because  of  the  presence  of  oxide, 
I  infer.  Nascent  hydrogen  with  the  sulphur  forms  some 
hydrogen  sulphide,  hence  the  stain  on  the  lead  paper  can- 
not be  satisfactorily  used  to  discriminate  between  the  mixed 
zinc  and  sulphur  and  the  zinc  sulphide.  This  applies  also 
to  the  iron  and  sulphur  in  Number  13/2.  The  hydrochloric 
acid  is  supplied  on  the  side  table.  It  is  of  commercial 
grade,  specific  gravity  about  1.16,  or  20°  Baume. 

Number  13/2.— The  iron  used  here  is  iron  dust,  the 
finest  powder,  designated  in  dealers'  catalogues  as  "  iron 
by  alcohol."  Unfortunately,  when  treated  with  hydro- 
chloric acid  the  gas  often  makes  a  stain  on  the  lead  paper. 

Number  13/3.— The  nitric  acid  is  supplied  on  the  side 
table.  The  concentrated  commercial  article,  specific  grav- 
ity 1.38,  or  40°  Baume,  serves  the  purpose.  The  gas  may 
bubble  quite  rapidly  through  the  acid  and  still  give  a  good, 
result. 


12    THE  ELEMENTARY   PRINCIPLES  OF   CHEMISTRY 

Number  15/j. — In  the  pupil's  hands  this  experiment 
may  fail  of  good  result  if  the  powder  is  too  coarse.  The 
iodine  may  then  sublime  without  much  action  on  the  lead. 
I  have  had  no  trouble  with  the  lead  dust,  but  this  is  sup- 
plied by  the  dealers  only  in  the  chemically  pure  grade. 
This  is  much  more  expensive,  and  the  purity  is  not  needed. 
In  lieu  of  this,  100-mesh  powder  of  commercial  grade  seems 
to  serve  the  purpose.  Even  the  still  coarser  powder  will 
react  if  the  heat  is  applied  slowly  and  the  mixture  shaken. 

Number  15/2. — I  have  found  magnesium  in  the  form  of 
ribbon  preferable  for  this  and  similar  experiments. 

Number  15/4. — The  oxidation  of  the  lead  is  slow,  espe- 
cially if  the  powder  is  coarse,  and  its  result  is  not  as  con- 
spicuous as  in  the  preceding  illustrations.  Still,  the  experi- 
ment gives  a  useful  observation  to  be  recalled  in  the  subse- 
quent experiments  with  lead  nitrate. 

Number  16/2. — The  zinc  nitrate,  being  very  deliquescent, 
is  best  given  out  in  small  quantities.  The  main  supply 
should  be  kept  well  stoppered. 

Number  17/lt — The  zinc  here  and  subsequently  used 
under  the  designation,  granulated  zinc,  is  chemically  pure 
(c.  p.),  Number  20,  in  the  dealers'  catalogues.  It  is  about  as 
coarse  as  granulated  sugar,  and  it  is  rather  important  in 
some  of  the  experiments  that  exactly  this  material  be  used. 

Number  17/2. — The  commercial  strong  sulphuric  acid  is 
used.  The  dilute  acid  called  for  in  the  experiment  is 
made  with  one  volume  of  acid  to  four  of  water,  and  I  pre- 
fer at  this  stage  of  the  work  to  have  only  this  dilute  acid 
supplied  on  the  side  table.  If  the  pupils  are  to  make  the 
dilution,  they  should  be  warned  as  to  the  manner  of  so 
doing.  (See  Number  519,  Part  II.) 

Number  18.— This  experiment  as  a  whole  takes  a  good 
deal  of  time,  although  its  several  steps  are  not  long.  I 
deem  it  well  worth  the  time,  for  it  is  a  difficult  matter  to 
bring  beginners  to  a  fair  understanding  of  the  phenome- 
non of  exchange,  because  of  the  difficulty  in  tracing  the 


SUGGESTIONS  TO  TEACHERS  13 

several  constituents  by  direct  observation.  In  practice  I 
find  that  alkaline  reaction  is  sometimes  obtained  in  the 
last  part  of  (/),  showing  the  presence  of  lime  in  the  pre- 
cipitate— due,  I  suppose,  to  insufficient  washing. 

Number  22. — Pupils  are  very  likely  to  overlook  the  need 
of  having  the  water  and  the  solute  at  the  same  ^temperature 
before  mixing.  This  condition  is  not  specified  in  the  direc- 
tions, but  if  the  student  deliberates  on  his  problem  as  he 
should,  his  common  sense  will  suggest  the  need.  When  I 
find  that  this  is  overlooked,  I  like  to  suggest  it  by  questions 
like  these :  What  is  your  problem  ?  (To  get  the  effect  of 
solution  simply.)  Suppose  you  had  some  sand  warmer  than 
the  water  and  mixed  it  with  the  water,  would  it  dissolve  ? 
What  would  be  its  effect  on  the  temperature  of  the  water  ? 
Suppose,  then,  that  the  salt  is  warmer  than  the  water,  what 
would  be  its  effect  on  temperature,  if  no  solution  took 
place  ?  How,  then,  must  you  observe  the  effect  of  solution 
simply  ?  I  let  them  assume  that  the  salt  has  the  tempera- 
ture of  the  room,  or  let  them  put  the  thermometer  into  the 
bottle  and  thus  observe  it. 

For  thermometric  experiments  I  use  the  so-called  "  chem- 
ical thermometers  "  of  the  dealers'  catalogues  with  the  scale 
up  to  150°  C.  engraved  on  the  stem.  They  vary  a  good  deal 
in  their  readings,  and  therefore  it  is  useful  to  attach  a  num- 
bered tag  to  each,  in  order  that  the  student  may  use  one 
thermometer  through  his  series  of  readings.  If  the  scale 
becomes  dim,  it  is  improved  by  rubbing  over  it  a  piece  of 
charcoal  or  a  soft  lead-pencil. 

Number  34/!. — The  mercuric  sulphocyanate  I  keep  at  my 
table  and  give  to  each  student  his  portion  as  he  brings  his 
dish.  The  substance  is  not  much  in  use,  and  there  may  be 
some  difficulty  in  getting  it  from  the  dealers,  although  I 
have  had  no  trouble.  To  omit  the  experiment  would  be  no 
serious  matter ;  it  is  introduced  rather  as  a  curiosity.  This 
substance  is  the  material  of  the  so-called  Pharaoh's  serpent, 
It  is  also  called  sulphocyanide. 


14    THE  ELEMENTARY  PRINCIPLES  OF   CHEMISTRY 

Numbers  34/2  and  34/3. — The  alternative  form  is  some- 
what simpler  of  construction,  but  the  first  has  the  advan- 
tage that  it  gives  the  instructor  opportunity  to  emphasize 
the  formation  of  two  products  of  combustion. 

Number  34/5. — The  sodium  hydroxide  is  supplied  on  the 
side  table,  preferably  as  a  solid.  The  sticks  should  be  broken 
in  pieces  about  an  inch  long  to  avoid  waste.  Two  or  three 
of  these  in  a  bottleful  or  beakerful  of  water  are  enough. 
For  counterpoising,  clean  gravel  kept  in  a  bottle  on  the 
side  table  is  convenient. 

Number  34/6. — In  quizzing  on  the  law,  I  cite  the  several 
reactions  which  have  already  occurred  in  the  work,  and  ask 
the  application  of  the  law  to  each  one,  calling  for  the  spe- 
cific naming  of  factors  and  products. 

Number  37. — It  is  important  that  the  hydrochloric  acid 
be  of  the  chemically  pure  (c.  p.)  grade.  This  is  diluted 
with  an  equal  volume  of  water.  It  is  well  thus  to  prepare 
at  the  start  sufficient  of  the  acid  to  serve  all  the  class, 
in  order  to  insure  uniformity  of  sample  for  the  whole  ex- 
periment. The  ammonium  hydroxide  is  the  commercial 
article,  "FFF,"16°  Baume,  or  specific  gravity  0.96,  used 
without  dilution.  Both  substances  leave  but  a  slight  stain 
on  evaporation.  They  are  supplied  on  the  side  table.  The 
portions  taken  by  the  pupil  to  his  own  table  should  not  be 
allowed  to  stand  long  unstoppered,  and  it  is  best  that  resi- 
dues be  not  returned  to  the  side-table  bottles.  I  use  the 
strips  of  paper  made  by  cutting  gummed  labels,  and  the 
measuring  test-tubes  thus  marked  should  be  preserved  to 
provide  for  repetition.  If  I  see  that  two  out  of  the  three 
results  obtained  are  good,  I  direct  repetition  of  only  the 
one.  This  may  be  made  independently,  provided  the  vol- 
umes are  preserved.  It  is  best  to  use  separate  measuring 
tubes,  one  for  the  acid  and  another  for  the  hydroxide. 
The  pupils'  ingenuity  is  taxed  somewhat  to  "  note  carefully 
the  volume  of  acid  used."  If  I  find  them  blundering,  I 
suggest  that  they  fill  the  tube  to  a  marked  strip,  pour  out 


SUGGESTIONS  TO  TEACHERS  15 

what  is  needed,  and  mark  the  level  of  the  residue  by  a 
second  strip.  The  directions  are  worded  on  the  supposi- 
tion that  test-tubes  with  gummed  strips  are  used  for  meas- 
uring. About  one  half  of  a  test-tubeful  should  be  used 
as  the  unit  volume. 

I  have  the  class  weigh  only  to  tenths,  and  I  hold  them 
to  results  that  show  a  variation  not  exceeding  0.2  of  a  grain 
from  the  ratio  of.  2:1:2.  A  good  proportion  of  the  results 
will  show  a  smaller  variation  than  this. 

Number  37/5.— In  quizzing  on  this  law,  as  on  Law  1, 
I  use  the  reactions  already  presented,  and  ask  the  applica- 
tion of  the  law  in  both  its  forms  to  each  one. 

Number  37/7. — This  paragraph  usually  puzzles  the  class 
a  good  deal.  In  quizzing  I  follow  a  line  like  this :  State 
the  converse  of  this  law.  Is  this  true  ?  Suppose  you  have 
in  hand  two  samples  of  matter,  A  and  B\  suppose  you 
ascertain  that  both  contain  the  same  constituents,  com- 
bined in  the  same  ratio  as  in  the  other  one,  does  it  follow 
that  A  and  B  are  samples  of  the  same  substance  ?  This 
usually  gives  occasion  to  say,  Learn  the  fact  now ;  the  ex- 
planation will  come  later. 

Number  37/8. — Some  may  object  to  the  alternative  state- 
ments as  tending  to  confuse.  The  first  is  so  commonly  the 
one  given  that  I  have  not  wished  to  omit  it;  and  yet,  it 
seems  to  me,  there  is  a  distinct  advantage  in  the  broader 
aspect  of  the  second  form.  This  is  conveniently  and  force- 
fully applied  to  any  reactions,  even  those  involving  four  or 
more  substances. 

Numbers  40/a  and  40/b. — I  find  it  a  good  plan  to  take  off 
altogether  the  metal  pans  of  the  balance  and  to  substitute 
glass  crystals.  In  weighing  out  the  mercury,  pupils  will  be 
awkward.  I  suggest  that  they  put  the  weights  on  the  right- 
hand  pan  and  pour  from  the  bottle  a  little  more  mercury 
than  is  necessary  to  counterpoise,  then  by  means  of  a  knife 
or  spatula  blade  separate  a  small  globule  and  push  it  off  the 
pan  and  into  the  bottle.  The  use  of  the  heavier  balance, 


16    THE  ELEMENTARY  PRINCIPLES  OP  CHEMISTRY 

in  order  to  check  the  total  weights,  is  not  very  material  to 
the  problem,  and  may  be  omitted  if  it  is  not  convenient  to 
provide  the  balance.  It  may  occur  once  or  twice  in  the 
class  that  the  reaction  is  spoiled  by  overheating.  It  is  well 
to  emphasize  from  the  desk  the  likelihood  of  this,  and  the 
precaution  of  using  a  little  alcohol.  The  heat  of  reaction 
evaporates  the  alcohol  if  too  much  be  not  used. 

In  color  the  mercuric  and  the  mercurous  iodide  are 
somewhat  variable,  and  they  are  sensitive  to  light.  The 
former  sometimes  responds  well  to  the  tests  even  if  the 
color  is  dull-red,  and  the  odor  of  the  iodine  gives  a  good 
indication  as  to  the  completeness  of  the  reaction:  The 
latter  often  shows  a  brown  tint.  In  both  instances  the  first 
test  by  alcohol  sometimes  shows  the  reaction  incomplete ; 
if  so,  the  rubbing  should  be  continued.  Mercury  and  iodine 
are  both  rather  expensive,  but  I  have  been  unable  to  find 
cheaper  practicable  material  which  will  illustrate  the  law  as 
clearly  and  as  conspicuously  as  these  do.  I  have  had  the 
experiment  long  in  use,  and  reckon  it  very  serviceable. 

Number  40/5. — To  show  that  this  law  is  not  contra- 
dictory to  Law  2,  gives  a  good  opportunity  for  questions  in 
the  class  discussion. 

Number  41. — Magnesium  in  the  form  of  ribbon  is  here 
preferable,  and,  if  it  is  tarnished,  pieces  of  emery  paper 
should  be  supplied  at  the  side  table  to  be  used  in  cleaning 
the  surface.  It  is  important  that  the  zinc  be  the  granu- 
lated, c.  p.,  as  already  specified.  The  nitric  acid  is  the  com- 
mercial article  described  in  Number  13/3.  The  crucible 
should  be  of  thin  porcelain,  Eoyal  Berlin,  or  equally  good, 
and  Number  1,  diameter  If  inches,  is  recommended  for  size. 
The  evaporating  dishes  also,  which  are  used  in  41/#,  should  be 
of  the  same  material,  3^  or  3J  inches  in  diameter,  and  glazed 
inside  and  outside.  These  stand  high  heat  with  little  break- 
age, but  the  cheaper  grades,  in  my  experience,  have  not  been 
satisfactory  for  such  experiments.  The  rod  should  be  short 
enough  to  lie  in  the  dish  without  danger  of  spilling  out. 


SUGGESTIONS  TO  TEACHERS  17  . 

Of  the  two  methods  given  in  41/j  and  41/5,  the  first  has 
the  advantage  of  directness  and  simplicity  of  reaction,  but 
there  is  sometimes  difficulty  in  carrying  the  reaction  to 
completeness  without  loss  of  oxide  or  without  prolonged 
heating.  Then,  too,  the  porcelain  is  likely  to  be  corroded 
by  reduction,  and  I  have  seen  the  nitride  formed  in  some 
instances.  The  product  is  often  very  dark-colored.  On 
the  other  hand,  the  second  method  gives  a  cleaner  reaction, 
although  less  direct  to  the  beginner,  but  it  involves  the  use 
of  iodine,  is  somewhat  more  difficult  in  manipulation,  and 
it  uses  smaller  quantities.  However,  I  have  found  the 
two  methods  together  very  instructive,  as  one  part  of  the 
larger  experiment.  It  is  not  necessary  that  the  magnesium 
should  be  entirely  dissolved  by  the  iodine,  as  small  frag- 
ments will  be  oxidized  in  the  final  heating.  The  mixture 
does  not  become  thoroughly  dry  on  the  water-bath.  But 
little  alcohol  is  needed.  The  tendency  is  to  use  an  excess, 
which  adds  to  the  difficulty  of  evaporation. 

I  find  that  75  per  cent  of  the  class  results  reach  1.59  ± 
0.04  grams  of  oxygen  for  2.40  grams  of  magnesium.  As  an 
error  of  0.02  in  the  weight  of  oxygen  is  multiplied  by  2.4 
in  the  final  result  of  the  first  method  and  by  4.8  in  the  sec- 
ond, the  range  is  fully  as  small  as  should  be  expected.  In 
the  experiment  with  zinc  about  the  same  proportion  of  the 
class  reach  1.59  ±  0.07.  Since  in  this  one  the  error  of 
0.02  in  the  weight  of  oxygen  is  multiplied  by  3.3,  a  varia- 
tion of  ±  0.07  or  even  more  is  to  be  expected.  The  range  of 
variation  in  both  cases  should  be  made  evident  and  be  dis- 
cussed in  the  class  room. 

Numbers  41/3  and  41/4.— The  scale  of  these  might  be  re- 
duced with  some  economy  of  time,  but  the  effect  of  error 
in  the  final  result  would  be  thus  increased.  On  the  whole, 
I  prefer  the  quantities  specified.  For  collecting  bottles  I  use 
the  ordinary  half-gallon  packing  bottles  with  glass  stopper. 
On  these,  both  bottle  and  stopper,  is  placed  a  number 
corresponding  with  the  number  of  the  individual  equip- 


18    THE  ELEMENTARY  PRINCIPLES  OF  CHEMISTRY 

ment  of  which  they  are  a  part.  Some  such  expedient  is 
important,  in  order  to  identify  each  bottle  with  its  content. 

For  graduated  flask,  I  have  found  latterly  one  of  1,200 
c.c.  capacity  more  convenient  than  one  of  750  c.c.  Com- 
mon flasks  of  the  right  capacity  are  easily  obtained,  and 
it  is  a  small  matter  to  graduate  these  with  sufficient  accu- 
racy, using  graduated  flasks,  and  placing  a  mark  with  a  file 
or  a  diamond  at  the  proper  point  of  the  neck.  This  effects 
a  considerable  economy  over  the  commercial  graduated 
flasks.  Thus  prepared  they  are  distributed  about  the 
laboratory  on  the  side  tables.  The  small  residue  of  water 
may  be  weighed  as  directed,  or  its  volume  may  be  measured 
in  the  small  cylinder. 

About  75  per  cent  of  the'  class  results  come  within  0.200 
±  0.006  for  the  hydrogen  by  magnesium  and  by  zinc.  By 
comparing  the  results  for  oxygen  and  for  hydrogen  in  the 
individual  pupil's  work,  the  practical  equivalence  often 
appears  even  when  the  partial  results  are  not  satisfactory, 
and  this,  indeed,  is  the  main  point  at  issue.  It  is  espe- 
cially recommended  that  there  be  thorough  quizzing  in  all 
the  details  of  the  manipulations,  observations,  and  calcula- 
tions before  the  corresponding  text  in  Part  I  is  taken  up. 
Then  there  should  be  thorough  drilling  on  the  law,  the 
corollaries,  and  the  definitions,  as  they  constitute  the  basis 
of  the  whole  system  which  is  to  follow.  It  may  be  sug- 
gestive to  recall  the  axiom,  Two  quantities  equal  to  a  third 
are  equal  to  each  other. 

Number  47/a, — The  dealers  supply  under  the  name  of 
"  dissolving-tubes  "  what  is  preferable  to  the  common  test- 
tube,  being  of  a  little  heavier  glass  and  of  smaller  diameter 
for  the  length.  The  size  9  X  f  inches  is  used.  The  unit- 
tube  may,  perhaps,  be  obtained  of  the  proper  size  under  the 
name  "  specimen  tube,"  but  it  is  easily  made  to  order  if  not 
in  stock.  For  rubber  bands  I  use  No.  8,  getting  them  in 
quarter-pound  packages.  It  is  a  great  convenience  to  get 
the  oxygen  of  dealers.  If  this  source  is  not  available,  this 


SUGGESTIONS  TO  TEACHERS  19 

part  of  the  experiment  might  be  omitted,  although  the 
necessary  quantity  of  oxygen  could  be  made  in  the  labora- 
tory without  much  trouble.  In  generating  the  dioxide, 
too  much  dilution  of  the  nitric  acid  interferes  with  the 
reaction. 

Pupils,  it  is  to  be  expected,  will  need  some  help  in  these 
first  gas  manipulations.  In  the  discussion  they  should  be 
guarded  against  the  error  of  assuming  that  the  residual 
gas  is  the  new  product  formed.  It  is  recommended  that 
they  be  called  upon  to  pick  out  illustrations,  especially  of 
the  fourth  and  fifth  laws,  from  the  data  of  Number  49, 
Part  I. 

The  volume  measurements  in  this  experiment  are  crude, 
but  I  have  found  it  useful,  as  it  makes  practicable  some 
illustration  of  volumetric  proportions  without  the  more  ex- 
pensive and  complicated  apparatus  that  would  otherwise 
be  needed.  If  the  Hofmann  lecture  apparatus  is  available, 
it  will  be  especially  helpful  to  show  the  class  experimen- 
tally the  volume  ratio  between  hydrogen,  oxygen,  and  water. 

Number  50/3. — Believing  that  the  energy  relations  of 
chemical  phenomena  should  not  be  ignored,  even  in  an  ele- 
mentary course,  I  have  introduced  this  experiment  to  illus- 
trate heat  of  neutralization.  u  The  oxalic  acid  is  the  crys- 
tallized commercial  article.  In  the  conditions  of  the 
experiment  the  rise  of  temperature  is  about  5°,  which  gives 
a  neutralization  heat  of  25,000  cal.  This  is  about  the 
book  value.  A  variation  of  0.5°  in  the  reading  makes  a 
difference  of  2,500  in  the  final  result. 

Number  62/2. — Problems  solved: 

S       =    31.8  =    50$ 
0      =    31.8  = 


S08  = 

63.6 

100 

Fe    = 

55.6  = 

63.6$ 

S      = 

31.8  = 

36.4$ 

FeS  = 

87.4  = 

100 

20    THE  ELEMENTARY  PRINCIPLES  OF   CHEMISTRY 


Zn 

=    64.9 

=    67.10 

S 

=    31.8 

=    32.90 

96.7 

100 

H2 

=      2. 

=      5.90 

S 

=    31.8 

=    94.10 

33.8 

100 

Fe 

=    55.6 

=    44.10 

C12 

=    70.4 

=    55.90 

126.0 

100 

Fe 

=  .  55.6 

=    34.50 

C13 

=  105.6 

=     65.50 

161.2 

100 

Pb 

=  205.3 

=    74.50 

C12 

=    70.4 

=    25.50 

275.7 

100 

Cu 

=    63.1 

=    39.80 

S 

=    31.8 

=    20.10 

04 

=    63.6 

=    40.10 

158.5 

100 

A12 

=    53.8 

=      5.70 

S4 

=  127.2 

=    13.50 

040 

=  636.0 

=    67.50 

K2 

=    77.6 

=      8.20 

H48 

=    48. 

=      5.10 

942.6 

ioo~ 

C2 

=    23.8 

=    39.90 

H4 

=      4. 

=      6.70 

02 

=    31.8 

=    53.40 

59.6 

100 

C2 

=    23.8 

=    92.20 

H2 

=      2. 

=      7.80 

25.8 

100 

SUGGESTIONS  TO  TEACHERS  21 

C6     =    71.4  =     92.2 
Hfi    =      6.    =      7.8 


77.4       100 

Number  65/6. — Problems  solved : 

1.  Fe  +  S  =  FeS. 

55.6  :  31.8  ::  75  :  x  =  42.9. 

2.  Zn  +  S  =  ZnS. 
64.9  :31.8  : :  x  :  50. 

x  =  102.0. 

3.  Zn  +  2HC1  =  ZnCl2  +  211. 
64.9  :  135.3  : :  x  :  50. 

x  =  24.0. 

4.  2XaOH  +  C02  =  Na2C03  +  H20. 
Na  =  22.9  C  =11.9 

0    =15.9  08  =  31.8 

H    =    1.0  43?T 

39.8 
(2  X  39.8)  :  43.7  : :  50  :  x. 

x  =  27.45  grams  C02. 
CaC03  +  2HC1  =  C02  +  CaCl2  +  H20. 
Ca  =  39.7  C  =11.9 

C    =11.9  08  =  31.8 

03  =47.7  43?f 

99.3 
99.3  :  43.7  : :  y  :  27.45. 

y  =  62.4  grams  CaC03. 

5.  HgI8  +  Hg  =  2HgI. 
Hg  =  198.5 

I8     =  251.8 

450.3 
450.3  :  198.5  : :  90  :  x. 

x  =  39.7  grams  Hg. 

6.  2NaOH  +  C02. 
79.6  :43.7  ::  10  :  x. 

x  =  5.49  grams  C02. 


22    THE  ELEMENTARY  PRINCIPLES  OF  CHEMISTRY 

CO  +  0  =  C02. 

(11.9  +  15.9)  :43.7  ny  :  5.49. 

y  =  3.49  grams  CO. 
(11.9  +  15.9)  :  15.9  ::  3.49  :  z. 

z  =  1.996  grams  0. 

?4?  =  2.79  +  liters  of  CO. 

=  1.395  liters  of  0. 
1.4o 

2.79  :.1.395  ::2  :  1. 
(Law  of  gas-volumetric  proportions.) 

7.  Mg  =  24.1.     H  =  1. 

2  :  17.9  :  :  x  :  10. 

x  —  1.117  grams  of  H. 
24.1  :2  n  y  :  1.117. 

y  =  13.46  grams  Mg. 

8.  The  first  contraction  is  12  vols.,  and  in  making  this, 
all  the  hydrogen  has  been  combined  ;  therefore 

3  :  2  :  :  12  :  x. 

s=  a 

Q 

—  X  100  =  80$  hydrogen. 

The  oxygen,  however,  is  not  all  combined,  since  con- 
traction follows  the  second  addition  of  hydrogen.  If  the 
total  residual  volume  of  3  (RV)  had  been  used  and  6  of 
hydrogen  added,  the  residual  would  have  been  in  the  same 
ratio  as  that  observed  —  that  is,  7.5  vols.  The  total  volume 
would  then  have  been  10  +  5  +  6,  and,  the  residual  being 
7.5,  the  contraction  would  have  been  13.5  vols.,  and  in  this, 
all  the  oxygen  is  combined  ;  hence 
3:1  ::13.5  :  y. 

y  =  4.5  =  90$  oxygen. 


27S    I    *>0 

9-  10°  x  x  =  lla34  c'c'  =  voL  at 


fare  --  am         vn  '' 

273  50°  and  760  mm. 

110.24  X  ~  =  116.36  c.c.  at  50°  and  720  mm. 


SUGGESTIONS  TO  TEA 


0   =15.9  |^  X  100  =  13.120  H. 

45'7  15.9 

X  100  =  34.8$  0. 


— 


•• 
"'=«'•      £ 

53.33  _  3.354 

1ST'  £354- 

Hence  the  coefficients  are  1,  2,  1,  and  the  formula  is 
CH20.  Pupils  will  need  to  be  guarded  against  the  error  of 
dropping  the  fractions  in  the  first  set  of  quotients,  and 
therefore  calling  the  coefficients  3,  6,  and  3. 

Number  66.  —  Possibly  instructors  may  find  other  meth- 
ods of  illustrating  Boyle's  Law  and  Charles's  Law  conven- 
iently accessible  in  the  equipment  of  the  physical  laboratory, 
and  in  some  circumstances  it  may  be  thought  unnecessary 
to  study  them  in  detail  ;  or,  to  perform  the  experiments 
before  the  class  may  be  deemed  sufficient.  It  is  much 
better,  however,  if  practicable,  to  give  every  pupil  the 
chance  to  perform  them  for  himself.  If  the  apparatus  de- 
scribed in  the  text  for  Boyle's  Law  is  used,  it  should  be 
prepared  beforehand  by  the  instructor  in  such  number  as 
may  be  thought  necessary.  I  use  the  gasometric  tubes 
therein  described,  and  for  jar  a  50  c.c.  cylinder  ungradu- 
ated.  For  linear  measurement,  a  foot-rule  is  cheaply  and 
easily  obtained.  For  economy  they  may  be  broken  in  two 
and  still  serve.  Pupils  will  often  carelessly  lift  the  tubes 
too  high  and  let  the  air  out.  It  is  quite  a  puzzle  to  them 
to  see  how  they  are  put  into  position.  This  is  done  by 
pouring  mercury  into  the  gasometric  tube  until  one  half  or 
two  thirds  full,  closing  with  the  thumb,  and  inverting  in  a 


24    THE  ELEMENTARY  PRINCIPLES  OF  CHEMISTRY 

sufficiently  wide  and  shallow  dish  of  mercury.  From  this 
the  tuhe  is  transferred  by  dipping  a  deflagrating  spoon 
under  its  mouth  and  carrying  it  in  this  position  to  the 
cylinder  previously  filled  with  mercury.  After  the  tube  is 
in  position  the  cylinder  may  be  partly  emptied  for  economy 
of  mercury.  The  cost  of  the  latter  is  the  chief  objection 
to  this  form  of  apparatus. 

This  experiment  gives  another  good  opportunity  to  dis- 
cuss the  limit  of  accuracy.  Inasmuch  as  the  reading  of 
volumes  is  limited  to  about  0.1  c.c.,  and  this  observed  value 
is  multiplied  by  about  30,  a  constancy  of  product  within 
three  or  four  units,  or  even  better,  is  realized. 

The  barometer,  if  nqt  already  understood,  should  be 
brought  before  the  class  and  explained  so  that  they  may 
realize  how  the  relative  pressures  are  measured  in  units  of 
length. 

Number  67. — The  apparatus  for  Charles's  Law  should  be 
prepared  beforehand.  In  Fig.  4  the  supporting  stand  is 
not  shown.  I  use  the  ordinary  iron  stand,  clamping  the 
tube  A  to  the  upright  rod  by  means  of  a  universal  clamp, 
and  supporting  the  shallow  dish  of  mercury  as  well  as  the 
boiling  flask  on  the  iron  rings.  The  tube  S  is  best  made 
of  rubber  for  flexibility.  A  smaller  quantity  of  water  than 
indicated  by  the  cut  is  better.  The  tube  A  is  12  inches 
long  and  1.5  inches  in  diameter.  It  can  easily  be  obtained 
of  dealers.  The  upper  stopper  is  cork,  the  lower  one  of 
rubber.  A  foot-rule  may  be  used  for  linear  measurements. 
The  calculation  of  results  I  have  not  given  in  full,  deeming 
it  better  to  let  the  pupil  try,  at  least,  to  reason  it  out.  It 
involves,  besides  Boyle's  Law,  only  the  application  of  the 
simplest  arithmetical  analysis,  but  it  is  surprising  how 
often  even  bright  students  stumble  in  such  a  matter.  The 
book  value  of  the  increment  is  0.00367.  The  experiment 
realizes  0.0037  ±  0.0001. 

The  following  results  are  taken  from  a  student's  note 
book: 


SUGGESTIONS  TO  TEACHERS  25 


Barometer  =  30  in. 

Initial  length  of  column  =    7  in. 

Final  length  of  column  =    5.75  in. 
Initial  pressure =30— 7      =  23  in. 
Final  pressure  =  30  —  5.75  =  24.25  in. 


Initial  temperature  =  18° 

Final  temperature  ,=  100° 

Rise  in  temperature  =  82° 

Initial  volume  =  12.5  c.c. 

Final  volume  =  15.3  c.c. 


12.5      x    23      =  287.5  c.c.       =  Initial  vol.  at  1  in.  and  18°. 
15.3      x    24.25  =  371.0  c.c.       =  Final  vol.  at  1  in.  and  100°. 
371.0     —  287.5    =    83.5  c.c.       =  Increase  of  vol  for  82°. 
83.5     -4-82      =      1.018  c.c.    =  Average  increase  of  vol.  for  1°. 
1.018  x     18       =    18.32  c.c.      =  Decrease  in  vol.  for  a  decrease  from 

18°  to  0°. 
287.5      —    18.32  =  269.18  c.c.      =  Initial  vol.  at  0°  and  1  in. 

1.018  -r-  269.18  =      0.0038  c.c.  =  Average  increase  for  1°  for  unit  vol. 

at  0°  =  coefficient  of  expansion. 

Number  71/a. — The  ordinary  test-tubes  (9  X  1)  are  used. 
It  is  recommended  that  they  and  also  the  rubber  stoppers 
and  strips  of  asbestos  board  be  prepared  beforehand  and 
distributed  as  needed.  The  loose  plug  is  quite  essential  to 
prevent  the  fine  dust  being  swept  out  of  the  tube  by  the 
current  of  gas.  A  source  of  error  is  the  loss  of  moisture  in 
addition  to  the  oxygen.  This  comes  chiefly  from  the  oxide, 
hence  the  preliminary  ignition.  I  have  found  the  chlorate 
usually  dry  enough  to  serve.  There  is  advantage  in  the 
use  of  the  oxide  because  of  the  lower  temperature  of  reac- 
tion, making  unnecessary  the  employment  of  hard  glass 
ignition  tubes.  The  directions  call  for  the  collection  of 
about  two  or  two  and  a  half  liters  of  gas.  Some  would 
prefer  a  smaller  scale  in  order  to  economize  time.  But  I 
deem  the  larger  scale  preferable,  as  in  41/3  and  41/4,  because 
the  error  in  weighing  has  less  effect  on  the  final  result. 

The  book  value  for  the  weight  of  the  liter  of  oxygen  is 
1.43  and  for  the  specific  gravity  15.9.  The  students  realize 
for  the  latter  about  16  ±  0.5. 

Number  81/lt — The  pupils  should  get  the  plan  of  this 
experiment,  first  and  second  steps,  before  beginning.  Of 
late  I  have  been  using  the  commercial  precipitated  chalk 
instead  of  marble  dust  for  the  calcium  carbonate,  and,  on 


26    THE  ELEMENTARY  PRINCIPLES  OF  CHEMISTRY 

the  whole,  I  believe,  like  it  better.  Wrapping  in  paper  (and 
perhaps  hi  addition  binding  with  a  rubber  band)  serves  to 
reduce  the  danger  of  loss  by  spray.  Kitric  is  preferable  to 
hydrochloric  acid,  because  it  gives  a  more  soluble  salt,  all 
of  which  remains  in  solution  in  the  given  conditions.  The 
intermediate  bottles  called  for  in  81/2  are  two-gallon  pack- 
ing bottles.  They  are  fitted  beforehand  with  rubber  stop- 
pers and  connecting  tubes,  and  are  supplied  in  considerable 
number,  serving  from  year  to  year.  I  have  a  few  pairs  of 
common  hand-bellows  hung  about  the  room  during  the 
progress  of  this  experiment. 

The  weight  of  carbon  dioxide  in  the  5  grams  of  the  car- 
bonate, assuming  the  purity  of  the  latter,  is  2.20  grams. 
The  tendency  is  to  get  too  large  results.  I  judge  that  75 
per  cent  of  the  determinations  will  not  exceed  2.25  grams, 
which  is  as  good  as  can  be  expected,  since  five  weighings 
are  necessary. 

The  measurement  of  volume  is  not  so  close.  The  vol- 
ume of  the  gas  at  0°  and  760  mm.,  which  weighs  (2.20  X  2) 
4.40  grams,  is  2.226  liters.  But  the  average  class  result  is, 
according  to  my  experience,  between  2.0  and  2.1  liters. 
This  brings  the  specific  gravity  nearer  24  than  22,  which 
can  not  be  regarded  a  very  satisfactory  determination,  and 
yet  I  find  that  it  serves  the  purpose  of  illustration  help- 
fully. 

Numbers  72-92. — This  law  of  Gay-Lussac  may  perhaps 
be  called  with  propriety  the  keystone  in  the  system  of  com- 
bining weights,  and  therefore  in  the  system  of  expressing 
the  quantitative  relations  of  chemical  phenomena.  To 
understand  it  is  therefore  very  important  for  beginning 
students.  The  reader  will  note  that  in  the  text  the  matter 
is  presented  and  discussed  without  using  the  conception  of 
atoms  and  molecules.  Some  teachers  may  think  this  too 
radical  a  departure  from  prevailing  methods,  but  my  con- 
viction grows  with  every  year's  experience  that  it  is  the 
wiser  method.  It  has  been  a  satisfaction  to  me  to  realize 


SUGGESTIONS  TO  TEACHERS  27 

that  these  fundamental  laws  may  be  clearly  presented  and, 
may  I  say,  assimilated  by  the  student  without  once  using 
the  words  atom  and  molecule.  I  have  maintained  this  plan 
through  the  text,  so  that,  as  I  have  elsewhere  said,  Chapter 
VII,  with  the  whole  conception  of  atoms  and  molecules,  may 
be  omitted,  and  if  I  mistake  not  with  no  disadvantage  to 
the  student.  Some  teachers,  no  doubt,  will  think  that  this 
topic  is  discussed  too  fully  and  too  early  in  the  course. 
I  can  only  say  that  I  do  not  agree  with  them.  As  to  the 
latter  point  it  seems  to  me  that  the  phenomenon  and  the 
relation  involve  no  serious  difficulty,  and  that  the  student 
can  as  well  appreciate  them  at  this  stage  as  after  more 
extensive  acquaintance  with  chemical  substances.  And 
surely  the  matter  is  very  fundamental. 

Numbers  95/2-95/5. — No.  8  shot  is  suitable.  The  zinc  and 
the  tin  are  preferred  in  granular  condition.  The  reading 
of  temperature  makes  the  chief  limitation  in  accuracy,  since 
it  must  be  uncertain  to  one  quarter  of  a  degree  at  least, 
and  this  is  a  large  fraction  of  the  quantity  to  be  measured. 
For  the  specific  heat  of  lead  I  find  the  class  results  average 
about  0.031  and  for  zinc  between  0.1  and  0.09. 

Numbers  lll/j-lll/f. — It  has  been  a  peculiar  satisfaction 
to  devise  an  easily  practicable  means  of  illustrating  experi- 
mentally the  phenomena  involved  in  Eaoult's  Laws.  The 
limitation  in  thermometric  reading,  as  in  the  specific  heat 
experiment,  prevents  a  good  quantitative  result.  But  when 
the  student  can  clearly  see  the  cause  of  inaccuracy  the 
objection  to  such  results  is  answered.  Certainly  these 
experiments  greatly  help  the  student  in  understanding 
Raoult's  laws.  The  substances,  common  camphor  and 
paraffin  and  white  crystallized  naphthalene,  are  easily  ob- 
tainable of  the  dealers.  The  quantities  of  solute  and  sol- 
vent are  so  chosen  as  to  give  depressions  of  2°  and  3°  for 
the  8-  and  12-per-cent  solutions  of  camphor,  and  2°  and  4° 
for  the  6-  and  12-per-cent  solutions  of  naphthalene.  These 
proportions  were  ascertained  by  preliminary  experiments 


28    THE  ELEMENTARY   PRINCIPLES  OF  CHEMISTRY 

with  a  thermometer  reading  to  tenths.  But  even  with  the 
finer  thermometer  and  somewhat  practiced  skill  the  con- 
stant obtained  for  camphor  is  38  and  for  naphthalene  42. 
Attention  is  called  to  the  specification  that  the  camphor  be 
dissolved  quickly  in  the  liquid  paraffin.  This  lessens  the 
risk  of  loss  by  volatilizing.  The  class  results  can  not  do 
more  than  give  some  notion  of  method  and  the  opportunity 
to  make  calculations.  The  data  quoted  in  Part  I,  with  per- 
haps some  additional,  must  be  relied  upon  to  give  an  ade- 
quate idea  of  the  phenomenon.  Even  the  results  of  the 
books  give  wide  departures  from  the  generalized  law.  And 
it  should  be  impressed  upon  the  student  that  the  approxi- 
mations to  the  law  in  these  matters  are  far  different  from 
those  of  the  laws  of  mass  in  Chapter  II. 

Numbers  127/1-127/7. — The  remarks  in  the  preceding  sec- 
tion as  to  thermometric  limitation  apply  here  also.  The 
pumice  is  supplied  in  small  lumps  on  the  side  table.  The 
sodium  acetate  is  that  designated  by  dealers  as  fused, 
granular,  pure.  The  potassium  tartrate  (not  acid  tartrate) 
is  granular  or  powdered,  and  pure.  The  potassium  chlo- 
ride and  ammonium  chloride  are  likewise  used  in  granular 
condition  and  pure.  In  127/2  and  127/3  the  quantities  are 
chosen  to  give  elevations  of  2°  and  4°  respectively;  in  127/4 
and  127/5  to  give  1°  and  2°  respectively ;  in  127/7  to  give  2° 
and  4°  for  potassium  chloride  and  the  same  for  ammonium 
chloride.  These  values  give  the  following  constants :  So- 
dium acetate,  10.9 ;  potassium  tartrate,  11.3 ;  potassium 
chloride,  9.6 ;  and  ammonium  chloride,  9.6.  It  must  be  ex- 
pected, however,  that  there  will  be  a  good  deal  of  variation 
in  the  class  results. 

Number  144. — The  tin  foil  should  be  pure.  It  is  easily 
obtainable.  The  white  powder  which  appears  as  the  first 
product  of  the  reaction  with  nitric  acid  is  metastannic  acid. 
Its  probable  composition  is  5Sn025H20.  The  final  product 
is  Sn02.  The  reaction  is  sufficiently  expressed  by  the  equa- 
tion ;  3Sn  -f-  4HNOs  =  SSnOg  +  4NO  -f-  2H80. 


SUGGESTIONS  TO  TEACHEHS  29 

The  quantitative  result  is  very  satisfactory.  The  value, 
1.34  grams  for  the  oxygen  with  5  grams  of  tin,  gives  29.6 
for  the  equivalent  weight  and  118.4  for  the  combining 
weight ;  while  the  value  1.35  grams  for  the  oxygen  gives 
29 A  and  117.6  respectively.  The  book  value  for  the  latter 
is  118.1.  The  class  results  come  easily  within  the  limits  of 
1.32  and  1.37,  although  a  variation  of  0.03  gram  might  be 
allowed  for  the  three  weighings  which  are  necessary.  It 
is  important  that  evidence  of  constant  weight  should  be 
secured  by  repeated  heating. 

In  quizzing  it  is  well  to  recall  the  use  of  nitric  acid  with 
hydrogen  sulphide,  Number  13/3,  and  with  ferrous  sulphate, 
Number  47/b,  for  the  purpose  of  oxidation  as  in  the  tin  ex- 
periment, and  to  contrast  this  use  with  that  in  which  sub- 
stitution is  the  primary  reaction,  Numbers  17/3  and  41 /g; 
further,  to  bring  out  the  fact  that  with  lead  and  zinc,  salts 
are  formed,  but  with  tin  no  salt  is  formed,  by  the  nitric 
acid. 

Additional  questions  like  these  are  suggested :  Defini- 
tion of  equivalent  weight?  of  combining  weight?  What 
would  be  the.  formula  of  this  oxide  of  tin,  if  29.5  were 
chosen  as  the  combining  weight  of  tin  ?  (Sn20.)  If  59.0 
were  chosen?  (SnO.)  If  88.5  were  chosen?  (Sn203.) 
Would  the  percentage  of  tin  expressed  by  these  several 
formulas  be  unchanged  ? 

Number  154. — The  sodium  carbonate  is  designated  as 
dry  and  chemically  pure  in  the  dealers'  catalogues.  It  is 
first  heated  gently  as  a  precaution,  although  probably  dry 
enough  without  heating.  There  is  need  of  care  that  the 
heating  be  not  excessive,  for  the  larger  evaporating  dishes 
are  easily  cracked  and  the  carbonate,  if  fused,  attacks  the 
porcelain.  The  quantitative  result  for  carbon  dioxide  is 
not  very  satisfactory,  being  considerably  too  large,  and  that 
for  the  sodium  oxide  too  small.  The  weight  of  the  former 
should  be  2.08  grams,  but  its  determination  involves  five 
weighings.  The  average  is  likely  to  be  nearer  2.3,  and  this 
8 


30    THE  ELEMENTARY   PRINCIPLES  OF   CHEMISTRY 

makes  necessarily  a  large  percentage  variation.  The  weight 
of  sodium  nitrate  should  be  8.02  grams  and  of  sodium 
oxide  2.92  grams.  The  average  result  is  likely  to  be  about 
7.75  for  the  former  and  2.82  for  the  latter.  These  values 
reckoned  as  percentages  give  46  for  carbon  dioxide  and  56.4 
for  sodium  oxide.  The  true  percentages  are  41.5  and  58.5. 

Using  the  former  percentages  as  basis  for  the  formula 
gives  46.  -=-  44  =  1.05 

56.4  -T-  62  =  0.91 
whereas  the  ratio  of  these  quotients  should  be  1 : 1. 

Nitric  acid  is  preferred  in  154/5  because  the  nitrate  is 
evaporated  to  dryness  a  little  more  easily  than  the  chloride. 
Hydrochloric  acid  is  specified  in  154/a  for  variety  in  the 
product. 

In  quizzing  it  should  be  made  clear  that  more  accurate 
determinations  would  show  results  like  these  : 
41.5  4-  43.7  =  0.9497 
58.5  -r-  61.7  =  0.9481 

Especially  should  the  pupil  be  guarded  against  the  error 
of  supposing  that  the  coefficients  1  and  1  are  chosen  be- 
cause these  quotients  approximate  1  sufficiently.  The 
choice  is  because  their  ratio  is  1 : 1 ;  and  in  this  the  ap- 
proximation is  much  closer.  Again,  let  it  be  made  clear 
that  this  ratio  is  a  direct  consequence  of  the  corollaries  of 
Law  4  (Numbers  42  and  46).  As  a  secondary  line  of 
thought  it  is  well  to  recall  the  experiments  Numbers  34/5, 
81/j,  and  81/2,  in  which  the  decomposition  of  a  carbonate 
was  studied  from  different  standpoints. 

Number  156.— Solution  of  problems: 

1.  92.30  -f-  11.9  —  7.76. 

7.70  -T-  1      =7.70.    Eatio  1  : 1 ;  but  (38  X  2)  -r- 12.9 
=  5.8  ;  hence  the  multiple  by  six  is  chosen,  C6H6. 

2.  40.      ^-  11.9  =  3.36.  Eatio,  1:2:1. 

6.67  -4-    1     =  6.67.          CH20  =  29.8. 
53.33  -r- 15.9  =  3.35.  (29  X  2)  -r-  29.8  =  2 ;  hence 

formula  is  C2H402. 


SUGGESTIONS  TO  TEACHERS  31 

3.  78.86  ^  11.9  =    6.63. 

10.60  -i-    1     =  10.60.         Ratio,  10  :  16.01  :  1 ;  hence 
10.53  ^-  15.9  =    0.662.  C10H160. 

4.  1.913  X  r^7  =  0.520  grams  carbon  =  52.0$. 

1.173  X  JL  =  0.131  grams  hydrogen  =  13.1$. 
i/.y 

1  _  (0.520  +  0.131)  =  0.349  grams  oxygen  =  34.9$. 
Formula  is  C2H60  =  combining  weight  45.7. 

5.  10.7  X  14.4  X  2  =  308  =  approximate  combining 

weight  of  the  chloride. 
6.2  ^  0.114  =  54  =  approximate   combining  weight 

of  iron. 

65.76  :  34.24  : :  35.2  :  x  —  18.33  =  exact  equivalent 

weight  of  iron. 

18.33  X  3  =  55.99  =  exact  combining  weight  of  iron. 
65.76  -v-  35.2  =  1.87. 

34.24  -T-  55.99  =  0.61.  Ratio  is  1  :  3  ;  hence  the  sim- 
plest formula  is  FeCl3,  with  the  combining  weight 
161.59,  but  the  chosen  formula  is  Fe2Cl6,  with  com- 
bining weight  323.2. 

6.  (35.2  X  100)  -r-  53.1  =  66.29$. 

7.  (125.9  X  100)  -5-  324.4  =  38.81$. 
(125.9  X  2  X  100)  -f-  450.3  =  55.91$. 

8.  0.36  :  1  : :  10  :  x  =  27.8  =  equivalent  weight  of  iron 

(in  FeClg). 

9.  121.7  :  47.7  : :  10  :  x  =  3.92  grams. 
10.  (43.7  X  100)  -5-  99.3  =  44.0$. 

Numbers  188-199. — It  should  not  be  expected  that  stu- 
dents will  hold  in  mind  much  of  these  introductory  para- 
graphs. They  will,  however,  gain  useful  impressions  from 
reading  them,  and  it  might  be  well  to  return  to  them  as  a 
kind  of  review  after  the  descriptions  have  been  finished. 

Number  202  (1).— It  is  recommended  that  the  experi- 
ment indicated  in  Fig.  2  be  exhibited  to  the  class  if  the 
apparatus  is  at  hand.  In  the  preparation  of  the  hydrogen 


32    THE  ELEMENTARY  PRINCIPLES   OF  CHEMISTRY 

by  the  class,  hydrochloric  acid  is  the  more  convenient.  If 
sulphuric  is  used,  the  dilute  (1  of  acid  to  4  of  water)  should 
be  supplied  on  the  side  table.  For  the  metal  I  use  nails. 

Number  203/i. — The  tubes  should  be  prepared  before- 
hand and  supplied  only  for  use  in  this  experiment.  They 
serve  from  year  to  year.  Convenient  dimensions  are  9  X  f 
inches.  The  plugs  are  about  |  inch  thick.  The  phenome- 
non is  due  to  the  fact  that  hydrogen  and  coal  gas  diffuse 
through  the  porous  partition  more  rapidly  than  air  does. 

Numbers  203/2  and  205, — These  make  good  experiments 
for  the  lecture  room.  The  platinum  sponge  is  made  by 
dipping  asbestos  fiber  in  a  solution  of  platinum  chloride, 
then  drying  and  igniting  it  in  the  gas  flame.  It  will  serve 
through  many  repetitions.  It  is  best  always  to  wrap  a 
towel  about  the  generator.  The  phenomenon  may  be 
shown  also  with  coal  gas  thus :  Hold  the  sponge  in  the 
flame  of  a  Bunsen  burner,  extinguish  the  flame,  and  let  the 
gas  stream  upon  the  sponge.  The  latter  glows,  and  some- 
times the  flame  is  relighted. 

Number  208. — The  hydrogen  from  common  iron  is  so 
impure  that  the  gas  from  the  generator  decolorizes  the 
permanganate. 

Number  210. — It  is  recommended  that  lithium  chloride 
be  exhibited  and  the  color  in  the  Bunsen  flame  be  shown 
from  the  lecture  table. 

Number  228/2. — Manganese  in  the  oxidizing  flame  is  vio- 
let or  amethyst,  in  the  reducing  flame  it  is  colorless,  but 
persistent  heating  is  necessary  to  remove  the  color. 

Number  255/1.— An  aniline  dyestuff  may  be  used  in  place 
of  the  permanganate.  The  latter  probably  loses  its  color 
in  part  by  reduction. 

Number  257/2.— The  charcoal  especially  prepared  for 
blowpipe  work  is  much  preferable  to  the  common  article. 

Number  237. — It  is  interesting  to  exhibit  glass  models 
of  famous  diamonds.  These  can  be  obtained  of  dealers, 
although  rather  expensive.  The  catalogue  price  for  a  col- 


SUGGESTIONS  TO  TEACHERS  33 

lection  of  twenty-one  of  the  largest  and  most  famous  is 
twenty-five  dollars. 

Number  243. — Samples  of  graphite  for  exhibition  can  be 
easily  obtained. 

Number  276. — Use  the  same  sodium  acetate  as  directed 
in  Number  127/2.  This  small  scale  of  preparation  is  suffi- 
cient. 

Number  280. — The  calcium  carbide  is  easily  obtainable. 
It  should  be  supplied  on  the  side  table  in  only  small  quan- 
tities, and  the  main  supply  should  be  carefully  protected 
from  moisture. 

Number  281. — The  mixing  of  acetylene  in  the  test-tube 
with  varying  quantities  of  air  shows  well  the  varying  nature 
of  the  combustion.  With  acetylene  alone  the  flame  is  very 
smoky  and  the  action  quiet,  but  with  the  suitable  quantity 
of  air  there  is  a  flash  of  bright  light  and  a  sharp  report.  By 
calculation  the  maximum  effect  should  be  when  2  volumes 
of  acetylene  are  mixed  with  25  volumes  of  air,  and  the  ex- 
periment shows  this  fairly  well.  It  is  best  not  to  ignite  at 
the  generator. 

Number  287. — Pieces  of  wire  gauze  5  or  6  inches  square 
are  supplied  at  the  side  table  only  for  this  experiment. 

Number  294. — It  is  interesting  to  show  samples  of  crude 
petroleum  and  the  commercial  products  obtained  from  it. 

Number  308. — There  can  not  be  too  much  caution  in 
using  phosphorus.  It  is  best  that  the  instructor  should 
keep  the  supply  at  his  own  desk,  himself  cut  suitable 
pieces — one  quarter  the  size  of  a  pea  is  more  than  enough — 
and  give  to  each  pupil,  when  he  is  ready  to  use  it,  only  one 
small  portion  at  a  time. 

Number  312. — A  flask  holding  about  250  c.c.  is  recom- 
mended— "round,  flat-bottom,  8  oz."  in  the  dealers' cata- 
logues. The  ammonium  nitrate  is  most  convenient  in  the 
crystallized  granular  form. 

Number  354. — An  interesting  experiment  for  the  lec- 
ture table  to  show  reversed  combustion  is  made  as  follows  : 


34    THE  ELEMENTARY  PRINCIPLES  OF  CHEMISTRY 

An  Argand  chimney  is  suitably  supported  by  a  universal 
clamp.  The  lower  end  of  the  chimney  is  fitted  with  a  cork. 
A  disk  of  asbestos  board  with  a  hole  in  the  middle  covers 
the  upper  end.  Through  the  cork  are  passed  two  glass 
tubes,  one  to  remain  fixed,  the  other  to  slide  somewhat 
easily  up  and  down.  By  the  first  tube  illuminating  gas  is 
led  to  the  interior  of  the  chimney.  The  second  tube  is 
attached  to  a  piece  of  rubber  hose.  Fill  the  chimney  with 
gas  and  ignite  the  latter  at  the  hole  in  the  asbestos  board, 
so  regulating  that  there  is  a  small  flame.  Push  up  the 
sliding  tube  until  its  open  end  is  about  one  half  inch  from 
the  flame.  Blow  gently  through  this  tube,  and  the  stream 
of  air  from  the  lungs  ignites  at  the  gas  flame.  Then  gently 
draw  down  the  air  tube,  and  the  flame  follows  with  it  and 
shows  the  air  burning  at  the  end  of  the  tube.  Call  atten- 
tion to  the  difference  between  the  two  flames.  The  air 
flame  is  almost  non-luminous,  as  there  is  no  separation  of 
solid  carbon. 

Number  361. — An  experiment  for  the  lecture  table  to 
show  the  formation  of  ozone : — A  small  bottle  or  beaker 
covered  with  a  glass  plate ;  into  this  is  placed  a  piece  of 
phosphorus,  a  stick  one  or  one  and  a  half  inches  long,  with 
freshly  cleaned  surface ;  also  a  little  water,  not  enough  of 
course  to  cover  the  phosphorus.  A  strip  of  starch  paper  is 
hung  in  the  bottle  over  the  phosphorus.  The  starch 
paper  is  made  by  dipping  filter  paper  into  a  fresh  thin 
starch  paste  to  which  a  little  solution  of  potassium  iodide 
has  been  added.  It  should  be  used  in  moist  condition. 
After  an  exposure  of  fifteen  or  twenty  minutes  the  paper 
shows  the  blue  color.  The  ozone  formed  -by  the  oxidation 
of  the  moist  phosphorus  liberates  iodine,  which  gives  the 
blue  color  with  the  starch. 

Number  366. — A  solution  of  hydrogen  dioxide  can  be 
obtained  of  the  chemical  dealers  and  usually  of  the  retail 
pharmacist. 

A  simple  experiment  is  to  show  its  decolorizing  effect 


SUGGESTIONS  TO  TEACHERS  35 

on  permanganate  acidulated  with  sulphuric  acid ;  also  the 
characteristic  test  by  adding  a  few  drops  of  the  dioxide  to 
a  very  dilute  solution  of  potassium  dichromate  acidulated 
with  sulphuric  acid  and  shaking  the  mixture  with  a  little 
ether.  The  latter  rises  to  the  surface  and  shows  a  fine  blue 
color  which  is  due  to  reaction  between  the  dioxide  and 
chromic  acid. 

Numbers  371-377/5. — It  is  recommended  that  some  of 
the  simple  tests  for  impurities  in  water  be  exhibited  on 
the  lecture  table.  For  hardness,  add  soap  dissolved  in 
water  or  alcohol,  first  to  distilled  water,  then  to  distilled 
water  to  which  a  little  calcium  or  barium  chloride  has  been 
added,  then  to  some  sample  of  natural  water.  For  chloride, 
add  a  few  drops  of  silver  nitrate  and  of  nitric  acid  first  to 
distilled  water,  then  to  water  to  which  a  few  drops  of  salt 
solution  have  been  added,  then  to  some  sample  of  natural 
water,  then  to  a  sample  of  water  polluted  with  sewage.  For 
ammonia,  test  samples  as  in  the  preceding  by  adding  potas- 
sium mercuric  iodide.  For  nitrite,  a  very  sensitive  test  is 
made  by  adding  a  solution  of  sulphanilic  acid  and  of 
naphthylamine  chloride,  if  these  reagents  are  at  hand.  Also, 
by  acidulating  with  sulphuric  acid  and  adding  potassium 
permanganate,  drop  by  drop,  may  be  shown  the  test  for 
"  oxygen  consumed."  These  are  the  tests  actually  used  in 
the  quantitative  examination  of  water. 

Number  378. — It  may  be  practicable  to  show  some  forms 
of  domestic  filters  and  perhaps  also  of  stills. 

Number  406. — Paraffin,  powdered  fluorspar,  and  sul- 
phuric acid  are  supplied  on  the  side  table.  The  acid  must 
be  concentrated,  but  the  commercial  grade  serves  the  pur- 
pose. The  lead  dishes  also  are  supplied  on  the  side  table 
for  only  this  experiment. 

Number  410. — The  sodium  is  best  kept  at  the  instruct- 
or's table  and  by  him  given  to  each  student  as  needed. 

Number  420/j. — It  is  deemed  best  in  this  first  study  of 
reactions  between  salts  in  solution  that  each  student  should 


36     THE  ELEMENTARY  PRINCIPLES  OP  CHEMISTRY 

prepare  the  several  solutions  from  the  solids  supplied  on 
the  side  table.  After  he  has  some  experience,  it  may  be 
expedient  to  supply  the  solutions  previously  prepared. 

Number  420/3.  —  Equations  completed  : 
2NaOH  +  CuS04  =  Cu02H2 


6NaOH  +  A12(S04)3  =  A1206H6  +  3Na2S04. 
NaOH  +NH4N03  =  XH4OH  +  NaNOs. 

Number  441/1(  —  Problems  solved  : 

1.  22.9  :  1  :  :  10  :  x  =  0.437  gram. 
0.437  -T-  0.0899  =  4.86  liters. 

2.  11.9  :  43.7  :  :  10  :  x  =  36.72  grams. 

36.72  -5-  1.98  =  18.55  liters  of  C02  and  18.55  liters  of  0. 

3.  Vap.  density  =  7.95.  —  3  liters.  —  3.575  grams. 

4.  1  liter  of  C02  and  1  liter  of  H. 

5.  Yap.  density  =  8.45,  1  liter  NH3  =  0.76  gram. 
16.9  :  53.1  :  :  0.76  :  x  =  2.39  grams  XH4C1. 

6.  The  ratio  of  combining  weights  16.9  :  39.8. 

7.  105.4  :  (84.5  X  2)  :  :  x  :  10. 

x  =  6.237  grams  Na2C03. 
(58.1  X  2)  :  105.4  ::  10  :  x  •=  9.07  grams  Na2C03. 

8.  11.9  :  105.4  :  :  1  :  x  =  8.857  grams  Xa2C03. 

9.  11.9  :  (40  X  2)  :  :  1  :  x  =  6.72  grams  MgO. 

10.  Acetylene.—  C2H2  +  50  =  2C02  +  H20. 

CH4  +  40  =  C02  +  2H20. 
Combustion    heat    of    acetylene  —  (97000  X  2)  -f- 

68400  +  47600  =  310000  cal. 
Combustion  heat  of  methane  =  97000  -f-  (68400  X  2) 

-  21800  =  212000  cal. 

Equal  volumes  of  the  two  gases  therefore  generate 
heat  in  the  ratio  of  310  :  212. 

11.  CaC2+  H20  =  C2H2+  CaO. 
63.5  :  25.8  ::  l.ix. 

x  =  0.406  Ib.  =  6.496  oz.  =  (6.496  -5-  1.17)  cu.  ft.  = 

5.55  cu.  ft.  of  acetylene  from  1  Ib.  of  CaC2. 
1000  :  x  :  :  310  :  212. 


SUGGESTIONS  TO>^MCHl$g  //        37 

^^[LlFOH^Jx^ 

x  =  684.     .  • .  1000  cu.  ft.  of  metBaioe"^684  cu.  ft, 

of  acetylene  in  heating  effect. 
684  cu.  ft.  obtained  from  (684  -^  5.55  =)  123.2  Ibs. 

of  CaC2. 
50  -=-  123.2  =  0.406  cent  per  Ib. 

Number  446/j. — Ammonium  hydroxide  is  always  on  the 
side  table.  Ammonium  chloride  and  carbonate  and  sodium 
carbonate  and  phosphate  may  suitably  be  supplied  in  solu- 
tion. 

Equations  completed : 

Mg  -f  0  =  MgO. 

Mg  +  2H20  =  MgOgH,  +  2H. 

Mg  +  2HC1  =  MgCl2  +  2H. 

Mg  +  H2S04  =  MgS04  +  2H. 

MgS04  +  2NaOH  =  Mg02H2  +  NagSO* 

MgS04  +  Na2C03  =  MgCQ3  -f  Na2S04. 

MgS04  +  Na2HP04  =  MgHP04  +  Ka2S04. 

Number  451, — The  aluminium  is  most  conveniently  sup- 
plied in  the  form  of  thin  sheet  or  of  wire.  Equations  for 
aluminium : 

A12(S04)3  +  6N"aOH  =  A1206H6  -f  3Na2S04. 
A1206H6  +  2NaOH  =  JSTa20  -A1203  +  4H20. 
A12(S04)3  +  6NH4OH  =  A1206H6  +  3(NH4)2S04. 
A12(S04)3  +  3Na2C03  +  3H20  =  AlAH6+3Na2S04+3C02. 
A12(S04)3  +  3^ra2HP04  =  A12(P04)2  +  3Na2S04  +  H3P04. 

Number  467. — It  is  well  to  exhibit  whatever  is  obtain- 
able of  the  natural  forms  of  silica  and  the  silicates,  also 
a  sample  of  alkaline  silicate,  the  so-called  soluble  glass. 

Number  474. — To  succeed  in  this  experiment  there  must 
be  used  a  liberal  proportion  of  the  carbonate,  and  the  heat- 
ing must  be  persistent.  The  especially  prepared  charcoal 
is  preferable,  as  in  other  blowpipe  experiments. 

Number  485. — Exhibit,  if  possible,  samples  of  apatite  or 
other  natural  phosphate  and  of  glacial  phosphoric  acid, 
also  of  the  phosphorus  chlorides. 


38     THE  ELEMENTARY  PRINCIPLES  OF   CHEMISTRY 

Numbers  486  and  487.— It  is  best  that  the  instructor 
himself  give  the  small  piece  of  phosphorus  to  each  student 
as  it  is  called  for.  Some  additional  illustrations  may  be 
made  on  the  lecture  table  ;  for  example,  a  small  fragment 
of  phosphorus  covered  with  powdered  charcoal  or  bone 
black  takes  fire  in  a  few  minutes.  If  a  small  fragment  is 
dissolved  in  carbon  disulphide  and  the  solution  is  absorbed 
by  filter  paper,  the  phosphorus  on  the  latter  takes  fire  by 
brief  exposure  to  the  air.  When  brought  in  contact  with 
iodine,  phosphorus  inflames. 

Number  507.— It  is  perhaps  well  to  exhibit  samples  of 
roll  sulphur,  sulphur  flowers,  and  precipitated  sulphur,  also 
the  crystallized  form,  on.  the  lecture  table,  although  they 
have  been  in  frequent  use.  More  important  is  it  to  show 
some  natural  substances — e.  g.,  native  sulphur,  pyrites,  and 
gypsum. 

Number  512. — Equations  completed: 
(NH4)2S  +  2HC1  =  H2S  +  2NH4C1. 
(NH4)2S8  +  2HC1  =  S  +  H2S  +  2NH4C1. 
+  NaXO3  =  0. 
+  MgS04  =  0. 

S  +  A18(S04)S  +  6H20  =  A1206H6  +  3(NH4)8S04  + 

3H2S. 

+  FeS04  =  FeS  +  (NH4)2S04. 
(:\TH4)2S  +  CuS04  =  CuS  +  (NH4)2S04. 

Number  515. — The  sodium  sulphite  is  of  commercial 
grade,  and  the  dried  and  powdered  condition  is  preferred, 
although  the  crystallized  probably  would  serve  nearly  as 
well. 

Number  517/lt — Equations  completed: 
S  +  20  =  S02. 
S02  +  H20  =  H2S03. 
H2S03  +  2NaOH  =  Na8S08  +  2H20. 
Na2S03  +  2HC1  =  S02  +  H20 
S02  +  0  =  S03. 


SUGGESTIONS  TO  TEACHERS  39 


H2S03  +  0  =  H2S04. 
Na2S03  +  0  =  JSTa2S04. 
H20  +  21  = 
K2OMn207 


Number  52  1/2.—  Equations  completed  : 
S03  +  H20  =  H2S04. 
H2S04  +  £NaOH  =  Na2S04  +  2H20. 
H2S04  +  NaOH  =  NaHS04  +  H20. 
Na2S04  +  20  =  ATa2S  +  2C02. 
H2S04  +  Ba012  =  BaS04  +  2HC1. 
Na8S04  +  SrCl2  =  SrS04  +  fcNaCl. 
JXTa2S04  +  Pb(A)2  =  PbS04  +  2Na(A). 

Number  531.  —  To  supplement  the  student's  observations 
it  is  recommended  that  the  properties  of  chlorine  be  fur- 
ther exhibited  by  experiments  at  the  lecture  table.  The 
following  are  suggested  :  Collect  chlorine  in  four  or  five 
glass  jars,  having  one  of  extra  depth.  Exhibit  with  these 
a  bottle  of  bromine  and  of  iodine  to  contrast  the  colors. 
Into  one  jar,  lower  the  lighted  taper  ;  into  another,  drop  a 
piece  of  filter  paper  which  has  been  dipped  in  turpentine  ; 
the  latter  should  be  heated  nearly  to  boiling  immediately 
before  the  paper  is  immersed  in  it,  in  order  that  it  shall 
burst  into  flame  when  dropped  in  the  chlorine.  Sometimes 
the  paper  only  chars.  In  the  third  jar,  show  the  bleaching 
effect  on  some  colored  stuff  —  e.  g.,  some  brightly  colored 
flower.  Into  the  fourth  jar,  lower  a  piece  of  phosphorus 
ignited  in  the  deflagrating  spoon.  Into  the  fifth  jar,  the 
deep  one,  shake  some  very  finely  pulverized  antimony,  pre- 
viously somewhat  heated  on  the  spatula  blade.  In  each 
case  the  fumes  are  so  irritating  that  the  jars  should  be  im- 
mediately placed  in  the  hood  or  otherwise  disposed  of. 

Numbers  537  and  540.—  To  show  from  the  lecture  table 
some  of  the  properties  of  the  chlorine  oxides  : 

1.  Pulverize  separately  a  little  potassium  chlorate  and  a 
little  white  sugar.  On  a  sheet  of  paper  thoroughly  mix 


40    THE  ELEMENTARY  PRINCIPLES  OF  CHEMISTRY 

about  equal  bulks  of  the  powders.  Place  in  an  earthen  dish 
or  suitable  substitute  a  small  quantity  of  the  mixture,  about 
what  could  be  heaped  on  a  copper  cent.  Let  a  drop  of 
concentrated  sulphuric  acid  fall  upon  this  from  a  rod  or 
small  pipette.  The  mixture  bursts  into  flame. 

2.  Place  in  a  mortar  a  small  quantity  of  potassium  chlo- 
rate, hardly  more  than  a  pin-head  in  size,  and  shake  on  this 
a  little  sulphur  powder.     Eub  with  the  pestle  under  some 
pressure,  and  the  mixture  explodes  with  considerable  noise. 

3.  Wrap  in  tin  foil  a  fragment  of  dry  phosphorus,  about 
the  size  of  a  pin-head,  and  potassium  chlorate  in  about 
equal  quantity.     Place  the  package  on  a  brick  and  explode 
it  by  a  sharp  blow  with  a  hammer. 

4.  Place  some  crystals  of  potassium  chlorate  in  a  pre- 
cipitating glass  or  a  small  cylinder.     Pour  water  on  this  to 
some   considerable   depth.     Drop   into  this  several  small 
pieces  of  phosphorus ;  then  by  means  of  a  pipette  let  flow 
upon  the  surface  of  the  chlorate  some  concentrated  sul- 
phuric acid,  a  little  at  a  time.     The  phosphorus  burns  with 
flashes  of  light  under  the  water. 

Number  534/j, — Equations  completed  : 

NaCl  +  H2S04  =  HC1  +  NaHS04. 

2HC1  +  Pb(C2H302)2  =  PbCl2  +  2HC2H302. 

HOI  +  AgN03  =  AgCl  +HN  08. 

HC1  +  HgN03  =  HgCl  +  HN03. 

HOI  +  MgS04  =  0. 

Number  567. — It  is  easy  to  give  some  idea  of  the  possible 
explosion  of  dust  in  air  by  the  following  experiment  for  the 
lecture  table :  A  plain  wood  box,  6  X  6  X  12  inches,  is  pro- 
vided. One  of  the  long  sides  is  open,  but  can  be  covered 
by  a  piece  of  window  glass.  The  box  is  placed  on  end  and 
a  lighted  taper  supported  by  a  flat  cork  is  put  inside,  also 
about  a  teaspoonful  of  flour  or  starch.  The  nozzle  of  a 
pair  of  bellows  is  inserted  through  a  hole  in  the  side  of  the 
box  and  the  glass  cover  is  put  over  the  open  side,  which  is 
turned  toward  the  class.  A  puff  of  air  from  the  bellows 


SUGGESTIONS  TO  TEACHERS  41 

raises  a  cloud  of  dust  which  is  inflamed  by  the  taper.  A 
flash  of  flame  is  seen,  and  often  the  glass  lid  is  thrown  off. 
It  is  interesting  to  exhibit  samples  of  black  and  of 
smokeless  gunpowders  and  of  gun  cotton,  which  are  easily 
obtainable. 

Number  584. — Equations  completed: 
CaO  +  H20  =  Ca02H2. 
Ca02H2  +  C02  =  CaC03  +  H20. 
Ca02H2  +  2HC1  =  CaCl2  +  2H20. 
CaCl2  +  (NH4)2C03  =  CaCOg  +  2NH4C1. 
CaCl2  +  (NH4)8C804  =  CaC2Q4  +  2NH4C1. 
Ca018+  Na2HP04  =  CaHP04 
CaCl2  +  Xa2S04  =  CaS04 

Number  5  88/i.— Problems  solved: 

1.  Mg  :  21  :  MgI2. 

24.1  :  (125.9  X  2)  :  275.9. 

2.  Dissolve  in  dilute  HC1,  evaporate  most  of  the  excess 
of  acid,  neutralize  the  rest  with  NH4OH,  precipitate  with 
solution  of  Na2HP04,  filter,  wash,  ignite,  and  weigh  the 
precipitate. 

3.  Mg  to  Mg2P207. 

(24.1  X  2)  :  221.1  ::!:&  =  4.587  grams. 

4.  Dissolve  directly  in  water  and  proceed  as  before. 
Mg  to  MgS04. 

24.1  :  119.5  ::l:x  =  4.959  grams  MgS04. 

5.  NO.  —  Dissolve    in    dilute    HC1,   precipitate   with 
NH4OH,  filter,  wash,  ignite,  and  weigh  the  precipitate. 
Alz  to  A1203—  (26.9  X  2) :  101.5  ::!:&=  1.887  grams  A1203. 

6.  24.1  :  (26.9  X  f).— Same  for  oxygen. 

7.  2NaOH  to  21. 

(39.8  X  2) :  (125.9  X  2)  : :  39.8  :  x  =  125.9  grams  I. 

8.  NagS04-10H20  [to]  BaCl2'2H20. 

320.2  :  242.6  : :  1  :x  =  0.758  gram  barium  chloride. 

9.  NaCl  to  AgN03. 

58.1  :  168.7  ::!:«  =  2.90  grams  AgN03. 


42    THE  ELEMENTARY  PRINCIPLES  OF   CHEMISTRY 

10.  6C1  to  2HN03. 

211.2  :  (62.6  X  2  =)  125.2. 

11.  NaN03;    in    ratio    of     combining    weights — i.    e., 
84.5:100.4,  or  1  :  1.19. 

12.  MgO  ;  40  :  55.6,  or  1  :  1.39. 

Number  601. — Equations  completed: 
Fe  +  2HC1  =  FeCl2  +  2R. 
Fe  +  H2S04  =  FeS04  +  2H. 

6FeS04+8HN03  =  2Fe2(S04)3+2NO  +  Fe2(N03)6  +  4H20. 
FeCl2  +  2NH4OH  =  Fe02H2  +  2NH4C1. 
FeCl2  +  2NH4HS  =  FeS  +  2NH4C1  +  H2S. 
2FeCl3  +  6NH4HS  =  SFeS  +  6NH4C1  +  3H2S  +  S. 
FeCl3  +  3NH4OH  =  FeQ3H^  +  3NH4C1. 

GENERAL  EQUIPMENT 

Lighting,  ventilation,  gas  and  water  supply,  and  drainage  are  mat- 
ters of  first  importance  in  the  chemical  laboratory;  but  to  treat  of 
them  is  beyond  the  scope  of  this  writing. 

There  is  one  item,  however,  in  the  furnishings  which  I  am  tempted 
to  urge  because  of  its  assistance  in  the  work  of  instruction  and  over- 
sight :  this  is  an  elevated  platform,  carrying,  if  possible,  a  small  demon- 
stration table,  from  which  the  instructor  may  see  fairly  well  what  is 
going  on  at  each  table,  and  from  which  he  may  give  explanations  and 
directions.  This  is  extremely  useful,  especially  when  large  sections 
must  be  handled  with  little  help.  It  would  be  useless  to  suggest 
dimensions  for  the  platform,  since  they  must  depend  on  the  size  and 
shape  of  the  room  and  other  unknown  conditions. 

The  items  of  apparatus  and  material  called  for  in  the  text  have 
been  already  specified  in  the  foregoing  paragraphs,  but  for  conven- 
ience they  are  here  summarized.  Prices  when  given  are  taken  from 
American  dealers'  catalogues. 

Balances. — The  balance  of  the  type  A,  Fig.  5,  in  the  Appendix,  is 
designated  in  the  dealer's  catalogue  (Fairbanks's)  as  the  Harvard  Trip 
Scale.  The  side  beam  which  carries  the  sliding  rider  gives  readings  from 
5  grams  to  0.1  of  a  gram.  Additional  weights  are  of  course  necessary. 
The  catalogue  price  without  weights  is  $7.50.  This  balance  is  called 
for  only  three  or  four  times  in  the  course,  and  if  economy  is  urgent 
could  be  omitted  from  the  equipment  without  serious  interference. 
The  other  balance  is  indispensable,  and  must  weigh  satisfactorily  to 


SUGGESTIONS  TO  TEACHERS  43 

0.01  of  a  gram.  Of  the  type  B,  Fig.  6,  Appendix,  the  cheapest  I  have 
found  now  in  the  market,  which  is  as  good  as  I  desire  for  my  own 
equipment,  is  designated  (Fairbanks's  catalogue)  as  the  Jeweler's  and 
Broker's  Scale ;  pans  3£  inches,  beam  7  inches,  length  of  box  12  inches ; 
price  without  weights  $8.50,  and  without  pans  $7.85.  1  prefer  to  sub- 
stitute glass  crystals  for  the  metallic  pans.  These  are  marked  in  some 
way  (e.  g.,  a  gummed  paper  label)  for  identification  and  counterpoised 
with  wire  or  foil,  and  thus  serve  as  well  as  the  especially  prepared 
glass  pans,  which  are  much  more  expensive. 

The  balance  of  the  type  C,  Fig.  7,  Appendix,  is  very  convenient,  and 
has  the  great  advantage  that  the  weights  are  attached.  The  one  figured 
is  known  as  the  Chaslin,  and  its  cost  is  $15,  which  of  course  includes 
weights.  The  hand  scales  with  horn  pans  are  recommended  by  some  ; 
they  are  much  cheaper,  but  I  have  no  experience  in  their  use. 

Thermometers,  chemical,  graduated  up  to  150°  C.,  price  $1.60 ;  or  a 
cheaper  grade  with  inclosed  paper  scale  up  to  150°  C.,  for  $1.10. 

A  barometer. 

Distilling  flasks,  capacity  about  200  c.c.  (6  oz.),  with  rubber  stop- 
pers to  fit,  for  Exps.  24  and  127. 

Combustion  apparatus,  for  Exp.  34/2  or  34/4. 

Graduated  flasks,  for  Exp.  41/3  (a).  See  also  Number  41/3  of  this 
pamphlet. 

Apparatus  for  Boyle's  Law,  Number  66. 

Apparatus  for  Charles's  Law,  Number  67. 

Test-tubes,  8  or  9  inches  x  1,  with  rubber  stoppers  (one  hole)  to  fit, 
and  asbestos  plug,  for  Exp.  71/A. 

Intermediate  bottles,  2  gal.,  acid  packing  bottles,  fitted  with  rubber 
stoppers  and  connecting  tubes,  for  Exp.  81/2.  See  Number  81/i,  this 
pamphlet. 

Bellows,  see  Number  81/i,  this  pamphlet. 

Diffusion  tubes,  glass  tubes,  9  x  f  inches,  with  porous  plug,  for 
Exp.  203/j. 

Porous  jar,  for  Exp.  203/2. 

Platinum  sponge,  for  Exp.  205,  see  Number  203  X2  of  this  pamphlet. 

Wire  gauze,  in  pieces  about  6x6  inches,  for  Exps.  287-289. 

Lead  dishes,  about  2  inches  in  diameter  and  f  inch  deep,  for  Exp. 
406. 

Files,  three-edged,  also  round. 

Cork-borers. 

Gummed  paper  slips. 

Rubber  bands,  No.  8.     See  Number  47/a. 

Corks  to  fit  smaller  test-tubes. 

Corks  to  fit  flasks,  Exp.  312. 


THE  ELEMENTARY   PRINCIPLES  OF   CHEMISTRY 


SIDE-TABLE  MATERIAL 

Sulphur,  roll,  Exps.  1-13. 

Sulphur  flowers  (sublimate),  Exps.  12/,,  12/a,  18/i,  13/a,  18/B. 

(Carbon  disulphide,  Exp.  12/a). 

Zinc  dust,  Exps.  13/a,  15/3. 

Iron  dust  (by  alcohol),  Exp.  13/2. 

Lead  dust,  or  lead  granulated,  No.  100,  commercial,  Exps.  15/,,  15/«, 
and  17/3. 

Zinc,  granulated,  c.  p.,  No.  20,  Exps.  17/i,  17/3,  17/4, 18/A,  41/2, 41/4, 
95/4,  and  others. 

Magnesium  ribbon,  Exps.  15/3,  41/l5  41/b,  41/3,  263,  445,  446. 

Iodine,  resublimed,  Exps.  i5/j,  18/A,  20/,,  40/a,  41/b,  and  some 
others. 

Lead  nitrate,  crys.  commercial,  Exps.  16/i,  18/A(c),  18/C(e). 

Zinc  nitrate,  crys.,  Exp.  16/2'. 

Copper  sulphate,  crys.  commercial,  Exps.  17/4,  21/4,  21/7,  24/>. 

Lime,  Exp.  18/B,  and  others. 

Alum,  potassic,  crys.  commercial,  Exps.  21/4,  21/7,  and  others. 

(Potassium  bichromate,  crys.);  see  Exp.  21/7. 

(Potassium  nitrate,  crys.  pure) ;  see  Exp.  21/7. 

Sodium  carbonate,  crys.,  or  sodium  phosphate,  crys.,  c.  p.,  Exps.  21/8, 
and  496. 

Sodium  hydroxide  (caustic),  pure,  sticks. 

Sodium  chloride,  commercial,  Exps.  22  and  24/8. 

Paraffin,  white,  hardest. 

Mercury,  Exps.  40/a  and  40/b. 

Mercuric  sulphocyanate  for  Exp.  34/i. 

Marble  chips. 

Iron  sulphate,  crude  (copperas). 

(Oxygen,  Exp.  47/a.) 

Oxalic  acid,  crys.  commercial,  Exp.  50/3. 

Potassium  chlorate,  crys.  or  powd.  commercial. 

Manganese  dioxide,  powd.  commercial. 

Calcium  carbonate,  precipitated,  commercial. 

Shot,  No.  8,  for  Exp.  95  A. 

(Tin,  granulated  commercial),  Exp.  95/5. 

Camphor,  refined,  Exps.  lll/i  and  lll/a. 

Naphthalene,  white  crys.,  Exps.  lll/8  and  lll/4. 

Pumice  in  small  pieces. 

Sodium  acetate,  pure,  fused,  powd.,  Exps.  127/a  and  127/s. 

Potassium  tartrate,  pure,  powd.,  Exps.  127/4  and  127/j. 


SUGGESTIONS  TO   TEACHEKS  45 

(Potassium  chloride,  c.  p.),  Exp.  127/7. 
(Ammonium  chloride,  c.  p.  crys.),  Exp.  127/7. 
Tin  foil,  pure,  Exp.  144. 
Sodium  carbonate,  c.  p.,  dry,  powd. 
Litmus  paper. 

For  the  Descriptive  Work  of  Chapter  VIII. — Nails ;  borax,  powd. ; 
copper  oxide,  black,  powd.;  sugar;  wood  shavings;  soft  coal;  char- 
coal ;  bone  black ;  iron  sulphide ;  lead  oxide  (litharge) ;  calcium  carbide ; 
phosphorus,  yellow ;  phosphorus,  red ;  ammonium  nitrate,  gran,  com- 
mercial ;  sodium  nitrate,  crys.  commercial ;  pieces  of  flannel  or  other 
woolen  stuff ;  calcium  fluoride,  powd.  (fluorspar) ;  sodium,  metallic ; 
magnesium  sulphate,  crys.  c.  p. ;  aluminium,  sheet  or  wire  ;  sand ;  sodium 
sulphite,  dried  powd. ;  sodium  sulphate,  dried  commercial ;  potassium 
hydroxide  (caustic),  sticks,  pure. 

Solutions. — Hydrochloric  acid,  commercial  (muriatic)  cone.,  20°  B, 
or  sp.  gr.  1.16. 

Nitric  acid,  commercial  cone.,  40°  B,  or  sp.  gr.  1.38. 

Sulphuric  acid,  commercial  dilute,  1  of  cone,  to  4  of  water. 

Sulphuric  acid,  cone,  commercial. 

Ammonium  hydroxide,  commercial,  16°  B,  FFF,  sp.  gr.  0.96. 

Hydrochloric  acid,  c.  p.,  dilute,  1  of  cone,  to  1  of  water.  For 
Exp.  37. 

Lead  acetate,  c.  p.,  1  of  salt  to  20  of  water. 

Alcohol. 

Potassium  permanganate,  dilute. 

Lime-water. 

Ammonium  chloride,  c.  p.,  1  to  10. 

Ammonium  carbonate,  c.  p.,  1  to  10. 

Ammonium  oxalate,  c.  p.,  1  to  25. 

Ammonium  sulphide  (yellow),  1  to  1. 

Sodium  phosphate,  c.  p.,  1  to  20. 

Silver  nitrate,  1  to  40. 

Barium  chloride,  c.  p.,  1  to  20. 

Strontium  chloride,  c.  p.,  1  to  20.    - 

Mercurous  nitrate,  1  to  30. 

INDIVIDUAL  EQUIPMENT 
Iron  stand,  3  rings. 
Funnel  support,  wood  bar. 
Tongs,  brass. 
Burner  and  hose,  2. 
Test-tube  stand. 
4 


46    THE  ELEMENTARY  PRINCIPLES  OF  CHEMISTRY 

Test-tubes,  10. 

Evaporating  dish,  about  4£  inches  diameter. 

Evaporating  dish,  Royal  Berlin,  3£  inches  diameter,  2. 

Crucible  and  lid,  Royal  Berlin,  No.  1. 

Beakers,  2. 

Rods,  3. 

Funnels,  2. 

Test-tube  brush. 

Sponge. 

Towel. 

Asbestos  board,  6  inches  square. 

Filter  paper,  common,  6  inches  diameter. 

Water-bath.  A  sauce-pan  of  granite  or  similar  ware,  about  5£  inches 
diameter  and  2£  deep,  with  two  zinc  covers,  makes  a  cheap  and  service- 
able water-bath. 

Pneumatic  trough.     One  of  zinc,  5  x  11  x  15  inches,  is  recommended. 

Spatula.  A  cheap  kitchen  knife  can  be  obtained  of  hardware  dealers, 
which  serves  well  and  is  much  less  expensive  than  the  spatula  of  chem- 
ical dealers. 

Saucer,  or  shallow  dish,  of  granite  or  earthenware,  4  or  5  inches 
diameter — e.  g.,  the  saucers  made  to  sell  with  flower  pots. 

Gas 'generator,  a  suitable  bottle— e.  g.,  a  5-oz.  "  quinine,"  fitted  with 
rubber  stopper  (2  holes). 

Thistle-tube. 

Rubber  hose,  1  ft.,  pure  gum,  f  in.  diam. 

Glass  tubing. 

Graduated  cylinder,  50  or  100  c.c. 

Collecting  bottle,  a  ^-gal.  "  acid  bottle,"  glass  stopper. 

Collecting  bottle,  small,  about  5  oz.,  wide  mouth,  2. 

Glass  covers,  2,  squares  of  window  glass  about  4x4  inches. 

Gasometric  tubes,  2.     See  Number  47/a,  this  pamphlet. 

Unit-tube.     See  Number  47/a,  this  pamphlet. 

Mortar  and  pestle,  about  3  in.  diam. 

Wire  gauze,  about  6x6  inches.  The  common  iron-wire  cloth,  which 
can  be  obtained  of  hardware  dealers,  serves  the  purpose,  and  is  much 
cheaper  than  brass  or  copper  gauze. 

Pipe-stem  triangle. 

For  the  descriptive  work  of  Chapter  VIII  are  needed  in  addition  : 

Flasks  and  corks.     See  Number  312,  this  pamphlet. 

Blowpipe. 

Platinum  wire,  3  inches,  fused  into  glass  handle. 

Combustion  or  deflagrating  spoon. 


SUGGESTIONS  TO  TEACHERS  47 

Crucible  lid  on  flat  cork. 
Taper. 

BOOKS  OF  REFERENCE 

WATTS.  Dictionary  of  Chemistry  (Morley  and  Muir),  4  vols. 
Longmans,  Green  &  Company. 

THORPE.  Dictionary  of  Applied  Chemistry,  3  vols.  Longmans, 
Green  &  Company. 

ROSCOE  and  SCHORLEMMER.  Treatise  on  Chemistry,  7  vols.  (Inor- 
ganic portion,  2  vols.)  D.  Appleton  &  Company. 

RAMSAY.    Inorganic  Chemistry.    P.  Blakiston,  Son  &  Company. 

REMSEN.  Inorganic  Chemistry  (Advanced).  Henry  Holt  &  Com- 
pany. 

RICHTER  (SMITH).  Inorganic  Chemistry.  P.  Blakiston,  Son  & 
Company. 

MENDELEEFF.  Principles  of  Chemistry.  Longmans,  Green  &  Com- 
pany. 

OSTWALD.     Outlines  of  General  Chemistry.     Macmillan  Company. 

WALKER.  Introduction  to  Physical  Chemistry.  Macmillan  Com- 
pany. 

TILDEN.  Introduction  to  Chemical  Philosophy.  Longmans,  Green 
&  Company. 

DOBBIN  and  WALKER.  Chemical  Theory  for  Beginners.  Macmil- 
lan Company. 

COOKE.     The  New  Chemistry.     D.  Appleton  &  Company. 

LOTHAR  MEYER.  Modern  Theories  of  Chemistry.  Longmans, 
Green  &  Company. 

MUIR.     Principles  of  Chemistry. 

VON  MEYER.     History  of  Chemistry.     Macmillan  Company. 

THORP,  F.  H.  Outlines  of  Industrial  Chemistry.  Macmillan  Com- 
pany. 

SADTLER.  Handbook  of  Industrial  Organic  Chemistry.  J.  B.  Lip- 
pincott  Company. 

NEWTH.  Chemical  Section  Experiments.  Longmans,  Green  & 
Company. 

EMERGENCIES 

Teachers  of  chemistry  have  a  heavy  responsibility  in  guarding 
against  serious  accident  by  close  and  constant  oversight  of  students' 
work.  Minor  accidents,  such  as  slight  burns  and  cuts  with  glass,  are 
likely  to  occur,  and  it  is  recommended  that  some  simple  materials  be 
kept  on  hand  for  use  in  emergency :  court-plaster,  clean  cotton,  mus- 


48    THE  ELEMENTARY  PRINCIPLES  OF  CHEMISTRY 

lin,  and  twine  for  bandaging :  for  burns,  sodium  bicarbonate,  vase- 
line, and  emulsion  of  lime-water  and  sweet  oil.  The  last  is  especially 
effective,  and  should  be  applied  liberally  to  the  burned  surface  to  protect 
it  from  the  air.  In  the  case  of  acid  burns,  treatment  with  dilute 
alkali  carbonate  or  hydroxide  should  come  first.  Acid  fumes,  if  in- 
haled, should  be  counteracted  by  cautiously  inhaling  ammonia.  The 
irritation  from  inhaling  chlorine  is  relieved  by  alcohol  fumes. 


TWENTIETH   CENTURY   TEXT-BOOKS. 


The  closing  years  of  the  nineteenth  century  witnessed  a  remarkable  awak- 
ening of  interest  in  American  educational  problems.  There  has  been  elaborate 
discussion  in  every  part  of  our  land  on  the  co-ordination  of  studies,  the  bal- 
ancing of  contending  elements  in  school  programmes,  the  professional  training 
of  teachers,  the  proper  age  of  pupils  at  different  stages  of  study,  the  elimina- 
tion of  pedantic  and  lifeless  methods  of  teaching,  the  improvement  of  text- 
books, uniformity  of  college-entrance  requirements,  and  other  questions  of  like 
character. 

In  order  to  meet  the  new  demands  of  the  country  along  these  higher 
planes  of  educational  work,  the  Twentieth  Century  Text-Books  have  been 
prepared. 

At  every  step  in  the  planning  of  the  series  care  has  been  taken  to  secure 
the  best  educational  advice,  in  order  that  the  books  may  really  meet  the  in- 
creasing demand  from  academies,  high  schools,  and  colleges  for  text-books 
that  shall  be  pedagogically  suitable  for  teachers  and  pupils,  sound  in  modern 
scholarship,  and  adequate  for  college  preparation. 

The  editors  and  the  respective  authors  have  been  chosen  with  reference  to 
their  qualifications  for  the  special  work  assigned  to  them.  These  qualifications 
are :  First,  that  the  author  should  have  a  thorough  knowledge  of  his  subject  in 
ks  latest  developments,  especially  in  the  light  of  recent  educational  discussions ; 
second,  that  he  should  be  able  to  determine  the  relative  importance  of  the 
subjects  to  be  treated  in  a  text-book ;  third,  that  he  should  know  how  to  pre- 
sent properly  his  topics  to  the  ordinary  student. 

The  general  editorial  supervision  of  the  series  is  in  the  hands  of  Dr.  A.  F. 
Nightingale,  Superintendent  of  High  Schools,  Chicago,  with  whom  is  asso- 
ciated an  advisory  committee  composed  of  an  expert  in  each  department  of 
study. 

The  offer  of  a  complete  series  of  text-books  for  these  higher  grades  of 
schools,  issued  under  auspices  so  favorable,  is  an  event  worthy  of  the  twentieth 
century,  and  a  good  omen  for  the  educational  welfare  of  the  future. 

One  hundred  volumes  are  comprised  in  the  series.  A  list  of  those  now 
ready,  and  of  others  in  preparation,  will  be  sent  upon  request. 

D.     APPLETON      AND      COMPANY,      NEW     YORK. 


TWENTIETH  CENTURY  TEXT-BOOKS* 

Uniform,  12mo. 

NOW    READY. 

Botanical  Text-Books  by  JOHN  MERLE  COULTER, 

A.  M.,  Ph.  D.,  Head  of  Department  of  Botany,  University  of  Chicago  : 
Plant  Relations.     A  First  Book  of  Botany.     Cloth,  $1.10. 
Plant  Structures.     A  Second  Book  of  Botany.     Cloth,  $1.20. 
Plant  Studies.     An  Elementary  Botany.     Cloth,  $1.25. 
Plants.     A  Text-Book  of  Botany.     Cloth,  $1.80. 
Key  to  Some  of  the  Common  Flora.     Limp  cloth,  60  cents. 

A  History  of  the  American  Nation.     By  ANDREW 

C.  MCLAUGHLIN,  A.  M.,  LL.  B.     Cloth,  $1.40. 

English  Texts.  For  College  Entrance  Requirements. 
Carefully  edited.  Per  volume,  cloth,  50  cents  ;  boards,  40  cents. 

Animal  Life.  A  First  Book  of  Zoology.  By  DAVID 
S.  JORDAN,  M.S.,  M.D.,  Ph.  D.,  LL.  D.,  and  VERNON  L.  KELLOGG, 
M.  S.  Cloth,  $1.20. 

The  Elements  of  Physics.  By  C.  HANFORD  HEN- 
DERSON, Ph.  D.,  and  JOHN  F.  WOODHULL,  A.  M.,  Ph.  D.  Cloth, 
$1.10.  With  Experiments,  $1.25. 

Physical  Experiments.  A  Laboratory  Manual.  By 
JOHN  F.  WOODHULL,  Ph.  D.,  and  M.  B.  VAN  ARSDALE.  Cloth,  with 
blank  pages,  60  cents.  Without  blank  pages,  limp  cloth,  45  cents. 

The  Elementary  Principles  of  Chemistry.     By 

ABRAM  VAN  EPS  YOUNG,  Ph.  B.    Cloth. 

A  Text-Book  of  Geology.  By  ALBERT  PERRY 
BRIGHAM,  A.  M.  Cloth,  $1.40. 

A  Text-Book  of  Astronomy.     By  GEORGE  C.  COM- 

STOCK,  Ph.  B.,  LL.  B.     Cloth,  $1.25. 

A  German  Reader.  By  H.  P.  JONES,  Ph.  D.  Cloth, 
$1.00. 

OTHERS    IN    PREPARATION. 

Send  for  complete  Prospectus  of  the  Twentieth  Century  Text- Books 
for  High  Schools, 

D.  APPLETON     AND     COMPANY,     NEW    YORK. 


TWENTIETH   CENTURY   TEXT-BOOKS. 


Plant   Relations. 

A  First  Book  of  Botany.  By  JOHN  M.  COULTER^ 
A.  M.,  Ph.  D.,  Head  of  Department  of  Botany, 
University  of  Chicago.  I2mo.  Cloth,  $>i.io  net. 

"'Plant  Relations'  is  charming  both  in  matter  and  style.  The  book  is 
superbly  manufactured,  letterpress  and  illustration  yielding  the  fullest  measure 
of  delight  from  every  page." — IV.  McK.  Vance,  Superintendent  of  Schools, 
Urbana,  Ohio. 

"  I  am  extremely  pleased  with  the  text-book,  *  Plant  Relations.'  " — H. 
W.  Conn,  Wesleyan  University,  Middletoivn,  Conn. 

"  Dr.  Coulter's  '  Plant  Relations,'  a  first  text-book  of  botany,  is  a  wholly 
admirable  work.  Both  in  plan  and  in  structure  it  is  a  modern  and  scientific 
book.  It  is  heartily  recommended." — Educational  Re-view. 

"It  is  a  really  beautiful  book,  the  illustrations  being  in  many  cases  simply 
exquisite,  and  is  written  in  the  clear,  direct,  and  simple  style  that  the  authoi 
knows  so  well  how  to  use.  A  very  strong  feature  of  the  work  is  the  promi- 
nence given  to  ecological  relations,  which  I  agree  with  Dr.  Coulter  should  be 
made  the  leading  subject  of  study  in  the  botany  of  the  preparatory  schools." — 
V.  M..  Spalding,  University  of  Michigan. 

"  We  can  hardly  conceive  of  a  wiser  way  to  introduce  the  pupil  to  the  fas- 
cinating study  of  botany  than  the  one  indicated  in  this  book." — Education. 

"The  book  is  a  marvel  of  clearness  and  simplicity  of  expression,  and  thatr 
too,  without  any  sacrifice  of  scientific  accuracy. " — School  Review. 

"It  marks  the  passage  of  the  pioneer  stage  in  botanical  work,  and  afford? 
the  student  a  glimpse  of  a  field  of  inquiry  higher  than  the  mere  tabulation  and 
classification  of  facts." — C.  H.  Gordon,  Superintendent  of  Schools,  Lincoln,  Neb. 

"  It  will  surely  be  a  Godsend  for  those  high-school  teachers  who  are  strug- 
gling with  insufficient  laboratory  equipment,  and  certainly  presents  the  most 
readable  account  of  plants  of  any  single  elementary  book  I  have  seen." — L.  M. 
Underwood,  Columbia  University. 

"  We  heartily  recommend  his  book  as  one  of  the  clearest  and  simplest  pres- 
entations of  plant  relations  that  we  have  seen." — Independent. 


D.  APPLETON   AND   COMPANY,  NEW  YORK- 


TWENTIETH  CENTURY  TEXT  BOOKS. 


A  History  of  the  American  Nation. 

By  ANDREW  C.  MCLAUGHLIN,  Professor  of 
American  History  in  the  University  of  Michi- 
gan. With  many  Maps  and  Illustrations.  i2mo. 
Cloth,  |i.4O  net. 

"  One  of  the  most  attractive  and  complete  one- volume  his- 
tories of  America  that  has  yet  appeared." — Boston  Beacon. 

"  Complete  enough  to  find  a  place  in  the  library  as  well  as  in 
the  school." — Denver  Republican. 

"This  excellent  work,  although  intended  for  school  use,  is 
equally  good  for  general  use  at  home." — Boston  Transcript. 

"It  should  find  a  place  in  all  historic  libraries." — Toledo 
Blade. 

"Clearness  is  not  sacrificed  to  brevity,  and  an  adequate 
knowledge  of  political  causes  and  effects  may  be  gained  from  this 
concise  history." — New  York  Christian  Advocate. 

"  A  remarkably  good  beginning  for  the  new  Twentieth  Cen- 
tury Series  of  text-books.  .  .  .  The  illustrative  feature,  and 
especially  the  maps,  have  received  the  most  careful  attention, 
and  a  minute  examination  shows  them  to  be  accurate,  truthful, 
and  illustrative." — Philadelphia  Press. 

"The  work  is  up  to  date,  and  in  accord  with  the  best  modern 
methods.  It  lays  a  foundation  upon  which  a  superstructure  of 
historical  study  of  any  extent  may  be  safely  built." — Pittsburg 
Times. 

"A  book  of  rare  excellence  and  practical  usefulness." — Salt 
Lake  Tribune. 

"The  volume  is  eminently  worthy  of  a  place  in  a  series  des- 
tined for  the  readers  of  the  coming  century.  It  is  highly 
creditable  to  the  author." — Chicago  Evening  Post. 

D.  APPLETON  AND   COMPANY,  NEW   YORK. 


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CIERS.    By  J.  TYNDALL,  LL.  D.,  F.  R.  S.    With  35  Illustrations.    $1.50. 

2.  PHYSICS  AND  POLITICS  ;   or,  Thoughts  on  the  Application  of  the  Prin- 

ciples   of  "Natural   Selection"  and   "Inheritance"  to  Political  Society. 
By  WALTER  BAGEHOT.    $1.50. 

3.  FOODS.    By  EDWARD  SMITH,  M.  D.,  LL.  B.,  F.  R.  S.    With  numerous  Illus- 

trations.   $1.75. 

4.  MIND  AND  BODY  :  The  Theories  of  their  Relation.    By  ALEXANDER  BAIN, 

LL.D.    With  4  Illustrations.    $1.50. 

5.  THE  STUDY  OF  SOCIOLOGY.    By  HERBERT  SPENCER.    $1.50. 

6.  THE  NEW  CHEMISTRY.    By  Professor  J.  P.  COOKE,  Harvard  University. 

With  31  Illustrations.    $2.00. 

7.  THE   CONSERVATION  OF  ENERGY.    By  BALFOUR   STEWART,  M.A., 

LL.D,,F.R.S.    With  14  Illustrations.    $1.50. 

8.  ANIMAL  LOCOMOTION  ;  or,  Walking,  Swimming,  and  Flying.    By  J.  B. 

PETTIGREW,  M.  D.,  F.  R.  S.,  etc.    With  130  Illustrations.     $1.75. 

9.  RESPONSIBILITY  IN  MENTAL  DISEASE.    By  HENRY  MAUDSLET,  M .  D., 

$1.50. 

10.  THE  SCIENCE  OF  LAW.    By  Professor  SHELDON  AMOS.    $1.75. 

11.  ANIMAL  MECHANISM  :  A  Treatise  on  Terrestrial  and  Aerial  Locomotion. 

By  Professor  E.  J.  MAREY,  College  of  France.   With  117  Illustrations.  $1.75. 

12.  THE  HISTORY  OF  THE  CONFLICT  BETWEEN  RELIGION  AND  SCI- 

ENCE.   By  J.  W.  DRAPER,  M.  D.,  LL.  D.    $1.75. 

13.  THE  DOCTRINE  OF  DESCENT  AND  DARWINISM.    By  Professor  OSCAR 

SCHMIDT,  Strasburg  University.    With  26  Illustrations.    $1.50. 

14.  THE  CHEMISTRY  OF  LIGHT  AND  PHOTOGRAPHY  IN  THEIR  AP- 

PLICATION TO  ART,  SCIENCE,  AND  INDUSTRY.    By  Dr.  HERMANN 
VOGEL,  Royal  Industrial  Academy  of  Berlin.   With  100  Illustrations.    $2.00. 

15.  FUNGI :  Their  Nature  and  Uses.    By  M.  C.  COOKE,  M.  A.,  LL.  D.    Edited  by 

the  Rev.  M.  J.  Berkeley,  M.  A.,  F.  L.  S.    With  109  Illustrations.    $1.50. 

16.  THE   LIFE   AND    GROWTH   OF   LANGUAGE.    By  Professor  WILLIAM 

DWIGHT  WHITNEY,  Yale  College.    $1  50. 

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JEVONS,  M.  A.,  F.  R.  S.    $1.75 

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Colors.    $2.00. 


2  The  International  Scientific  Series.— (Continued.) 

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EDEN,  University  of  Louvain.    With  83  Illustrations.    $1-50. 

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tions.   $1.50. 

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sity of  Halle.    With  91  Illustrations.    $1.75. 

22.  THE   THEORY    OF  SOUND  IN  ITS  RELATION  TO  MUSIC.    By  Pro- 

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Illustrations.    $1.50. 

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With  7  Photographic  Illustrations  of  Spectra,  and  52  other  Illustrations. 
$2.50. 

24.  A  HISTORY  OF  THE   GROWTH  OF  THE  STEAM-ENGINE.    By  Pro- 

fessor R.  H.  THURSTON,  Cornell  University.   With  163  Illustrations.    $2.50. 

25.  EDUCATION  AS  A  SCIENCE.    By  ALEXANDER  BAIN,  LL.  D.    $1.75. 

26.  STUDENTS'    TEXT-BOOK  OF  COLOR  ;  or,  Modern  Chromatics.    With 

Applications  to  Art  and  Industry.    By  Professor  OGDEN  N.  ROOD,  Colum- 
bia College.    With  130  Illustrations.    $2.00. 

27.  THE  HUMAN  SPECIES.    By  Professor  A.  DE  QUATREFAGES,  Museum  of 

Natural  History,  Paris.     $2.00. 

28.  THE  CRAYFISH  :    An  Introduction  to  the  Study  of  Zoology,    By   T.  H. 

HUXLEY,  F.  R.  S.    With  82  Illustrations.    $1.75. 

29.  THE   ATOMIC    THEORY.     By  Professor  A.  WURTZ.      Translated  by  E. 

Cleminshaw,  F.  C.  S.    With  Illustrative  Chart.    $1.50. 

30.  ANIMAL  LIFE  AS  AFFECTED  BY  THE  NATURAL  CONDITIONS  OF 

EXISTENCE.     By  Professor    KARL   SEMPER,   University  of  Wfirzburg. 
With  106  Illustrations  and  2  Maps.    $2.00. 

31.  SIGHT  :  An  Exposition  of  the  Principles  of  Monocular  and  Binocular  Vision. 

By  Professor  JOSEPH  LE  CONTE,  LL.D.,  University  of  California.    With 
132  Illustrations.    $1.50. 

32.  GENERAL  PHYSIOLOGY  OF  MUSCLES  AND  NERVES.    By  Professor 

I.  ROSENTHAL,  University  of  Erlangen.    With  75  Illustrations.    $1.50. 

33.  ILLUSIONS  :  A  Psychological  Study.    By  JAMES  SULLY.    $1.50. 

34  THE  SUN.  By  Professor  C.  A.  YOCJNG,  College  of  New  Jersey.  With  83 
Illustrations.  $2.00. 

35.  VOLCANOES  ;   What  they  Are  and  What  they  Teach.     By  Professor  JOHN 

W.  JUDD,  F.  R  S.,  Royal  School  of  Mines.     With  96  Illustrations.    $2.00. 

36.  SUICIDE  :  An  Essay  in  Comparative  Moral  Statistics.    By  Professor  HENRY 

MORSELLI,  M.  D.,  Royal  University,  Turin.       With  4  Statistical   Maps. 
$1.75. 

87.  THE  FORMATION  OF  VEGETABLE  MOULD,  THROUGH  THE  AC- 
TION OF  WORMS.  With  Observations  on  their  Habits.  By  CHARLES 
DARWIN,  LL.  D.,  F.  R.  S.  With  15  Illustrations.  $1.50. 


The  International  Scientific  Series.— (Continued.) 


88.  THE  CONCEPTS  AND  THEORIES    OF  MODERN  PHYSICS.    By  J.  B. 

STALLO.    $1.75. 

39.  THE  BRAIN  AND  ITS  FUNCTIONS.    By  J.   LUYS,  Hospice  Salpgtridre, 

Paris.    With  6  Illustrations.    $1.50. 

40.  MYTH  AND  SCIENCE.    By  TITO  VIGNOLI.    $1.50. 

41.  DISEASES  OF  MEMORY  :   An  Essay  in  the  Positive  Psychology.    By  Tn. 

RIBOT,  author  of  "  Heredity.'1    $1.50. 

42.  ANTS,  BEES.  AND  WASPS.      A  Record  of  Observations  of  the  Habits  of 

the  Social  Hymenoptera.    By  Sir  JOHN  LUBBOCK,  Bart.,  F.  R.  S.,  etc.   $2.00. 
43-  THE  SCIENCE  OF  POLITICS.    Bjr  Professor  SHELDON  AMOS.    $1.75. 

44.  ANIMAL  INTELLIGENCE.    By  GEORGE  J.  ROMANES,  M.  D.,  F.  R.  S.  $1.75. 

45.  MAN  BEFORE  METALS.    By  Professor  N.  JOLT,  Science  Faculty  of  Tou- 

louse.   With  148  Illustrations.    $1.75. 

46.  THE    ORGANS    OF    SPEECH    AND    THEIR   APPLICATION    IN    THE 

FORMATION   OF  ARTICULATE    SOUNDS.     By  Professor  G.  H.  VON 
MEYKB,  University  of  Zurich.    With  47  Illustrations.    $1.75. 

47.  FALLACIES  :  A  View  of  Logic  from  the    Practical  Side.      By   ALFRED 

SIDGWICK,  B.  A.,  Oxon.    $1.75. 

48.  ORIGIN  OF  CULTIVATED  PLANTS.    By  ALPHONSE  DE  CANDOLLE.   $2.00. 

49.  JELLY-FISH,   STAR-FISH,  AND  SEA-URCHINS.    A  Research  on  Primi- 

tive Nervous  Systems.     By  GEORGE  J.  ROMANES,  M.  D.,  F.  R.  S.    With  63 
Illustrations.    $1.75. 

50.  THE  COMMON  SENSE  OF  THE  EXACT  SCIENCES.    By  WILLIAM  KING- 

DON  CLIFFORD.    With  100  Figures.    $1.50. 

51.  PHYSICAL  EXPRESSION  :  Its  Modes  and  Principles.    By  FRANCIS  WAR- 

NER,  M.D.,  Assistant  Physician,  London  Hospital.    With  51  Illustrations. 

$1.75. 

52.  ANTHROPOID    APES.     By  Professor  ROBERT  HARTMANN    University  of 

Berlin.    With  63  Illustrations.    $1.75. 

53.  THE  MAMMALIA  IN  THEIR  RELATION  TO  PRIMEVAL  TIMES.    By 

Professor  OSCAR  SCHMIDT,  University  of  Strasburg.    With  51  Illustrations. 
$1.50. 

54.  COMPARATIVE  LITERATURE.    By  Professor  H.  M.  POSNETT,  M.  A.,  Uni- 

versity College,  Auckland.     $1.75. 

55.  EARTHQUAKES  AND  OTHER  EARTH  MOVEMENTS.  By  Prof essor  JOHN 

MILNE,  Imperial  College  of  Engineering,  Tokio.    With  38  Figures.    $1.75. 

56.  MICROBES,  FERMENTS,  AND  MOULDS.    By  E.  L.  TROUESSART.    With 

107  Illustrations.     $1.50. 

57.  THE  GEOGRAPHICAL  AND  GEOLOGICAL   DISTRIBUTION  OF  ANI- 

MALS.   By  Professor  ANGELO  HEILPRIN,  Academy  of  Natural  Sciences, 
Philadelphia.    $2.00. 

58.  WEATHER.    A  Popular  Exposition  of  the  Nature  of  Weather  Changes  from 

Day  to  Day.    With  96  Diagrams.    By  Hon.  RALPH  ABERCROMBY.    $1.75. 


The  International  Scientific  Series.—  (Continued.) 


59.  ANIMAL  MAGNETISM.    By  ALFRED  BINBT  and  CHARLES  FERE,  Assistant 

Physician,  Hospice  Salpgtriere,  Paris.    With  15  Figures.    $1.50. 

60.  INTERNATIONAL  LAW,  with  Materials  for  a  Code  of  International  Law. 

By  Professor  LEONE  LEVI,  King's  College,  London.    $1.50. 

61.  THE   GEOLOGICAL  HISTORY  OF  PLANTS.    With  79  Illustrations.    By 

Sir  J.  WILLIAM  DAWSON,  LL.  D.,  F.  R.  S.    $1.75. 

82.  ANTHROPOLOGY.  An  Introduction  to  the  Study  of  Man  and  Civilization. 
By  EDWARD  B.  TTLOR,  D.  C.  L.,  F.  R.  S.  With  78  Illustrations.  $2.00. 

33.  THE  ORIGIN  OF  FLORAL  STRUCTURES,  THROUGH  INSECT  AND 
OTHER  AGENCIES.  By  the  Rev.  GEORGE  HENSLOW,  M.A.,  etc.  With 
88  Illustrations.  $1.75. 

84.  THE  SENSES,  INSTINCTS,  AND  INTELLIGENCE  OF  ANIMALS,  WITH 
SPECIAL  REFERENCE  TO  INSECTS.  By  Sir  JOHN  LUBBOCK,  Bart., 
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65.  THE   PRIMITIVE   FAMILY   IN   ITS    ORIGIN   AND  DEVELOPMENT. 

By  Dr.  C.  N.  STARCKE,  University  of  Copenhagen.    $1.75. 

66.  PHYSIOLOGY  OF  BODILY  EXERCISE.     By  F.  LAGRANGE,  M.D.    $1.75. 

67.  THE   COLORS   OF  ANIMALS  :    Their  Meaning   and  Use.     By  EDWARD 

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68.  SOCIALISM :  New  and  Old.    By  Professor  WILLIAM  GRAHAM,  M.  A.,  Queen's 

College,  Belfast.    $1.75. 

69.  MAN  AND  THE  GLACIAL  PERIOD.    By  Professor  G.  FREDERICK  WRIGHT, 

D.  D.,  Oberlin  Theological  Seminary.    With  108  Illustrations  and  3  Maps. 

$1.75. 

70.  HANDBOOK  OF  GREEK  AND  LATIN   PALAEOGRAPHY.    By  EDWARD 

MAUNDE  THOMPSON,  D.  C.  L.,  etc.    $2.00. 

71.  A    HISTORY    OF    CRUSTACEA.      Recent    Malacostraca.      By  the  Rev. 

THOMAS  R.  R.  STEBBING,  M.  A.    With  51  Illustrations.     $2.00. 

72.  RACE  AND  LANGUAGE.    By  Professor  ANDRE  LEFEVRE,  Anthropological 

School,  Paris.    $1.50. 

73.  MOVEMENT.     By  E.  J.  MAREY.     Translated  by  ERIC  PRITCHARD,  M.  A., 

M.  B.,  B.  Ch.  (Oxon.).    With  200  Illustrations.    $1.75. 

74.  ICE-WORK,  PRESENT  AND  PAST.     By  T.  G.  BONNET,  D.  Sc.,  F.  R.  S., 

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75.  WHAT  IS  ELECTRICITY  ?     By  JOHN  TROWBRIDGE,  S.  D.,  liumford  Pro- 

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i7.  THE  AURORA  BOREALIS.  By  ALFRED  ANGOT,  Honorary  Meteorologist 
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78.  MEMORY  AND   ITS  CULTIVATION.    By  F.  W.  EDRIDGE-GREEN,  M.  D.f 

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79.  EVOLUTION  BY  ATROPHY.     By  JEAN  DEMOOR,  JEAN  MASSART,  and 

EMILE  VANDERVELDE. 


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PIONEERS  OF  EVOLUTION,  from   Thaies  to 

Huxley.  By  EDWARD  CLODD,  President  of  the  Folk-Lore 
Society  ;  Author  of  "  The  Story  of  Creation,"  "The  Story  of 
'  Primitive'  Man,"  etc.  With  Portraits.  I2mo.  Cloth,  $1.50, 

"  The  mass  of  interesting  material  which  Mr.  Clodd  has  got  together  and 
voven  into  a  symmetrical  story  of  the  progress  from  ignorance  and  theory  to 
knowledge  and  the  intelligent  recording  of  fact  is  prodigious.  .  .  .  The 
'  goal '  to  which  Mr.  Clodd  leads  us  in  so  masterly  a  fashion  is  but  the  start- 
ing point  of  fresh  achievements,  and,  in  due  course,  fresh  theories.  His 
book  furnishes  an  important  contribution  to  a  liberal  education." — London 
Daily  Chronicle. 

"  We  are  always  glad  to  meet  Mr.  Clodd.  He  is  never  dull ;  he  is  always 
well  informed,  and  he  says  what  he  has  to  say  with  clearness  and  precision. 
.  .  .  The  interest  intensifies  as  Mr.  Clodd  attempts  to  show  the  part  really 
played  in  the  growth  of  the  doctrine  of  evolution  by  men  like  Wallace,  Dar- 
win, Huxley,  and  Spencer.  .  .  .  We  commend  the  book  to  those  who  want 
to  know  what  evolution  really  means. " — London  Times. 

"  This  is  a  book  which  was  needed.  .  .  .  Altogether,  the  book  could 
hardly  be  better  done.  It  is  luminous,  lucid,  orderly,  and  temperate.  Above 
all,  it  is  entirely  free  from  personal  partisanship.  Each  chief  actor  is  sym- 
pathetically treated,  and  friendship  is  seldom  or  never  allowed  to  overweight 
sound  judgment." — London  Academy. 

"  We  can  assure  the  reader  that  he  will  find  in  this  work  a  very  useful  guide 
to  the  lives  and  labors  of  leading  evolutionists  of  the  past  and  present. 
Especially  serviceable  is  the  account  of  Mr.  Herbert  Spencer  and  his  share  in 
rediscovering  evolution,  and  illustrating  its  relations  to  the  whole  field  of 
human  knowledge.  His  forcible  style  and  wealth  of  metaphor  make  all  that 
Mr.  Clodd  writes  arrestive  and  interesting." — London  Literary  World. 

"  Can  not  but  prove  welcome  to  fair-minded  men.  .  .  .  To  read  it  is  to 
have  an  object-lesson  in  the  meaning  of  evolution.  .  .  .  There  is  no  better 
book  on  the  subject  for  the  general  reader.  .  .  .  No  one  could  go  through 
the  book  without  being  both  refreshed  and  newly  instructed  by  its  masterly 
survey  of  the  growth  of  the  most  powerful  idea  of  modern  times." — Thk 
Scotsman. 


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CHEMISTRY  OF  COMMON  LIFE.  By 
the  late  Prof.  JAMES  F.  W.  JOHNSTON.  A  new  edition,  revised 
and  enlarged,  and  brought  down  to  the  present  time,  by  ARTHUR 
HERBERT  CHURCH,  M.  A.,  Oxon.,  author  of  "  Food  :  its  Sources. 
Constituents,  and  Uses."  Illustrated  with  Maps  and  numerous 
Engravings  on  Wood.  I2mo.  Cloth,  $2.00. 

SUMMARY  OF  CONTENTS.  —  The  Air  we  Breathe.  —  The  Water  we  Drink.  —  The  Soil 
we  Cultivate.  —  The  Plant  we  Rear.  —  The  Bread  we  Eat.  —  The  Beef  we  Cook.  —  The 
Beverages  we  Infuse.  —  The  Sweets  we  Extiact.  —  The  Liquors  we  Ferment.  —  The 
Narcotics  we  Indulge  in.  —  The  Poisons  we  Select.  —  The  Odors  we  Enjoy.  —  The  Smells 
we  Dislike.  —  The  Colors  we  Admire.  —  What  we  Breathe  and  Breathe  for.—  What, 
How,  and  Why  we  Digest.  —  The  Body  we  Cherish.  —  The  Circulation  of  Matter. 

N  FOODS.  By  EDWARD  SMITH,  M.  D.,  LL.  B., 
F.  R.  S.,  Fellow  of  the  Royal  College  of  Physicians  of  London, 
etc  I2mo  Cloth,  $1.75. 

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of  diagrams,  displaying  the  effects  of  sleep  and  meals  on  pulsation  and  respiration,  and 
of  various  kinds  of  food  on  respiration,  which,  as  the  results  of  Dr.  Smith's  own  experi- 
ments, possess  a  very  high  value."  —  London  Examiner. 


O 


POISON  PROBLEM;  or,  The  Cause  and  Cure 
of  INTEMPERANCE.  By  FELIX  L.  OSWALD,  M.  D.,  au- 
thor of  "Physical  Education,"  "Household  Remedies,"  etc. 
I2mo.  Cloth,  75  cents  ;  paper,  25  cents. 

"The  author's  discussion,  with  the  startling  array  of  terrible  facts  with  which  he 
fortifies  his  argument  in  favor  of  total  abstinence  for  the  individual  and  prohibitory 
legislation  by  the  State,  fully  justifies  the  use  of  his  title.  He  treats  in  successive 
chapters  of  the  secret  of  the  alcohol  habit,  the  causes  of  intemperance,  the  physiological 
effects  of  the  poison  habit,  costs  of  intemperance,  alcoholic  drugs,  prohibition  and  sub- 
jective remedies.  Dr.  Oswald  is  a  radical  temperance  reformer.  He  denies  to  alcohol 
any  of  the  properties  of  food,  regards  it  solely  and  purely  as  a  poison,  and  one  of  the 
most  destructive  and  pernicious  of  poisons  at  that.  Temperance  reformers  and  workers 
will  find  the  book  an  arsenal  of  weapons  for  the  warfare  they  are  waging  on  intemper- 
ance." —  Boston  Traveller. 

TTEALTH   PRIMERS.       Edited   by   J.    LANGDON 
f*    DOWN,  M  D.,  F.  R.  C.  P.  ;  HENRY  POWER,  M.  B.,  F.  R.  C.  S.  ; 
J.  MORTIMER  GRANVILLE,  M.  D.  ;  JOHN  TWEEDY,  F.  R.  C.  S. 
In  square  i6mo  volumes.     Cloth,  40  cents  each. 

I.  Exercise  and  Training.—  II.  Alcohol:  Its  Use  and  Abuse.—  III.  Premature 
Death:  Its  Promotion  or  Prevention.—  IV.  The  House  and  its  Surroundings.—  V.  Per- 
sonal  Appearance  in  Health  and  Disease.  —  VI.  Baths  and  Bathing.  —  VII.  The  Skin 
and  its  Troubles.—  VIII.  The  Heart  and  its  Functions.—  IX.  The  Nervous  System. 

"These  little  volumes  deal  with  subjects  of  pressing  importance,  and  if  they  serve, 
as  they  should,  to  arouse  public  attention  to  sanitary  problems,  they  will  be  worth  their 
weight  in  gold."  —  Boston  Journal. 

D.  APPLETON  AND  COMPANY.  NEW  YORK. 


The  Races  of  Europe. 

A  Sociological  Study.  By  WILLIAM  Z.  RIPLEY, 
Ph.  D.,  Assistant  Professor  of  Sociology,  Massa- 
chusetts Institute  of  Technology  ;  Lecturer  in  An- 
thropology at  Columbia  University,  in  the  City  of 
New  York.  Crown  8vo,  cloth;  650  pages,  with  85  Maps 
and  235  Portrait  Types.  With  a  Supplementary  Bibliography  of 
nearly  2,000  Titles,  separately  bound  in  cloth,  issued  by  the 
Boston  Public  Library.  178  pages.  -  -  -  -  Price,  $6.00 

"  One  of  the  most  fascinating  sociological  and  anthropo- 
logical studies  that  have  been  offered  of  late  to  the  public.  .  .  . 
The  book  is  one  to  be  studied  with  care,  and  it  is  a  pleasure 
to  commend  it  as  most  helpful  to  sociological  students." 

Chicago  Evening  Post. 

"Will  win  the  approval  of  all  thoughtful  readers;  and  the 
care,  patience,  skill,  and  knowledge  with  which  it  is  planned, 
and  the  highly  satisfactory  manner  in  which  the  plan  is  car- 
ried out,  call  for  the  very  highest  praise." 

Boston  Saturday  Evening  Gazette. 

"One  of  the  most  important  works  of  the  year." 

New  York  Mail  and  Express. 

"A  valuable  and  interesting  book.  .  .  .  Will  attract  the 
attention  of  all  students  of  anthropology  and  all  its  kindred 
subjects.  While  it  will  most  deeply  interest  advanced  schol- 
arly readers,  it  at  the  same  time  abounds  in  value  for  those 
not  among  the  learned  classes. ' '  Chicago  Inter-  Ocean. 

"An  important  work  in  the  domain  of  anthropology  and  a 
book  of  supreme  interest  at  the  present  moment." 

Chicago  Times-Herald. 

"  Not  only  a  profound  sociological  study  but  a  scholarly 
contribution  to  the  science  of  anthropology  and  ethnology  by 
an  eminent  authority."  Philadelphia  Press.. 

D.     APPLETON     AND     COMPANY,     NEW    YORK. 


LITERATURES  OF  THE  WORLD. 

Edited  by  EDMUND  GOSSE, 

Hon.  M.  A.  of  Trinity  College,  Cambridge. 
Each,  J2mo,  cloth,  $J.50. 

Chinese   Literature. 

By  HERBERT  A.  GILES,  M.  A.,  LL.  D.  (Aberd.), 
Professor  of  Chinese  in  the  University  of 
Cambridge. 

"Few  recent  histories  of, literature  are  more  pregnant  with 
new  and  interesting  material  than  this.  There  is  nothing  like  it 
in  any  library,  and  one  may  say  with  assurance  that  there  is  not 
a  dull  page  in  it." — Boston  Transcript. 

"Information  and  instruction  share  its  pages  with  enlivening 
wit  and  wisdom,  and  it  can  be  confidently  relied  upon  for  many 
hours  of  pure  delight." — Chicago  Evening  Post. 

"Any  private,  public,  or  school  library  that  fails  to  place  it 
on  its  shelves  would  be  guilty  of  almost  culpable  indifference 
to  the  most  opportune,  the  most  instructive,  the  most  fascinating 
of  Asiatic  masterpieces  that  has  ever  been  garnered  into  a  single 
volume." — Brooklyn  Daily  Eagle. 

"The  work  is  done  with  sympathy,  with  insight,  and  with 
that  openness  of  mind  which  is  so  essential  in  dealing  with  the 
life  and  thought  of  the  East.  The  quality  of  the  poetry  will 
surprise  those  who  have  thought  of  the  Chinese  as  dealing  in  pru- 
dential maxims  and  in  philosophy  of  the  moral  life  rather  than  in 
the  stuff  of  the  imagination." — The  Outlook. 

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NOV    15  1933 

FEB      7  1938 

SEP  201941*' 

V:      ' 

LD  21-100m-7,'33 

YU 


